Method and apparatus for information transmission and reception in satellite communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method performed by a terminal in a wireless communication system is provided. The method includes: receiving configuration information on one or more sets of PUCCH repetitions from a base station; receiving DCI for scheduling the PDSCH from the base station; receiving a PDSCH from the base station based on the DCI; determining a plurality of slots for PUCCH repetition based on the configuration information if the one or more numbers of sets include a single value or based on the configuration information and DCI if the one or more numbers of sets include more than one value; and transmitting a PUCCH (Physical Uplink Control Channel) including HARQ-ACK information for the PDSCH to the base station on the determined plurality of time slots.

Description

Technical Field

[0001] The present disclosure relates to communication systems, and in particular to methods for transmitting and receiving control information in a satellite communication system. Background Art

[0002] 5G mobile communication technology defines a wide frequency band, making high transmission rates and new services possible, and can be realized not only in "below 6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands (including 28 GHz and 39 GHz) called millimeter waves. In addition, it has been considered to implement 6G mobile communication technology (called super 5G system) in terahertz frequency bands (e.g., 95 GHz to 3 THz frequency bands) in order to achieve a transmission rate fifty times faster than 5G mobile communication technology and an ultra-low latency that is one-tenth of 5G mobile communication technology.

[0003] At the beginning of the development of 5G mobile communication technology, in order to support services and meet the performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC) and massive machine type communications (mMTC), standardization of the following technologies is already underway: beamforming and massive MIMO for mitigating radio wave path loss and increasing radio wave transmission distance in millimeter waves; parameter sets supporting dynamic operation (e.g., operating multiple subcarrier spacings) for efficient use of millimeter wave resources and time slot formats; initial access technology for supporting multi-beam transmission and broadband; definition and operation of BWP (bandwidth part); new channel coding methods (e.g., LDPC (low-density parity check) codes for large amounts of data transmission and polarization codes for highly reliable transmission of control information); L2 preprocessing; and network slicing for providing dedicated networks dedicated to specific services.

[0004] Currently, in view of the services supported by 5G mobile communication technology, discussions on the improvement and performance enhancement of initial 5G mobile communication technology are ongoing, and there is already physical layer standardization on technologies such as: V2X (Vehicle to Everything) that assists driving decisions of autonomous vehicles based on information about the location and status of the vehicle transmitted by the vehicle and improves user convenience; NR-U (New Radio Unlicensed) that aims to ensure that system operations comply with various regulatory requirements in unlicensed bands; NR UE energy saving; Non-Terrestrial Network (NTN), which is UE-satellite direct communication for providing coverage in areas where terrestrial network communications are not available; and positioning.

[0005] In addition, the following technologies are being standardized in terms of air interface architecture / protocols: Industrial Internet of Things (IIoT) to support new services through interworking and integration with other industries; IAB (Integrated Access and Backhaul) to provide nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner; mobility enhancements including conditional switching and DAPS (Dual Active Protocol Stack) switching; and two-step random access (2-step RACH for NR) to simplify the random access process. The following technologies are also being standardized in terms of 5G system architecture / services: baseline architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software-defined network (SDN) technologies; and mobile edge computing (MEC) for receiving services based on UE location.

[0006] With the commercialization of 5G mobile communication systems, the number of connected devices, which has been growing exponentially, will be connected to the communication network, and it is therefore expected that there will be a need to enhance the functions and performance of 5G mobile communication systems and the integrated operation of connected devices. To this end, new research related to the following technologies is planned: Extended Reality (XR) for effectively supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), etc.; Improving 5G performance and reducing complexity by utilizing artificial intelligence (AI) and machine learning (ML); AI service support; Metaverse service support and drone communication.

[0007] In addition, such developments in 5G mobile communication systems will serve not only as a basis for developing: new waveforms for providing coverage in the terahertz band for 6G mobile communication technology; multi-antenna transmission technologies such as full-dimensional MIMO (FD-MIMO), array antennas, and large antennas; metamaterial-based lenses and antennas for improving the coverage of terahertz band signals; high-dimensional spatial multiplexing technology using OAM (orbital angular momentum); and RIS (reconfigurable smart surface), but will also serve as a basis for developing: full-duplex technology for increasing the frequency efficiency of 6G mobile communication technology and improving system networks; AI-based communication technology for achieving system optimization by utilizing satellites and AI (artificial intelligence) from the design stage and internalizing end-to-end AI support functions; and next-generation distributed computing technology for implementing services at a complexity level that exceeds the limits of UE operating capabilities by utilizing ultra-high-performance communication and computing resources.

[0008] With the development of wireless communication systems as described above, various services can be provided, and thus a way of efficiently providing these services, particularly, a way of optimizing a non-public network, is required.

[0009] On the other hand, as the cost of satellite launches has dropped significantly in the late 2010s and 2020s, the number of operators seeking to provide communication services via satellite is increasing. As a result, satellite networks are emerging as next-generation network systems that complement existing terrestrial networks. Satellite networks cannot yet provide a user experience comparable to that of terrestrial networks, but their advantage is that they can provide communication services in areas where it is difficult to establish terrestrial networks or in disaster situations, and as explained previously, economic feasibility is guaranteed due to the recent rapid reduction in satellite launch costs. Additionally, some companies and the 3GPP standards organization are also promoting direct communications between smartphones and satellites.

[0010] The above information is presented as background information only to assist in understanding the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above may be used as prior art for the present disclosure. Summary of the invention

[0011]

Technical issues

[0012] The present disclosure intends to provide an apparatus and method that can effectively provide a service in a wireless communication system such as a satellite communication system.

[0013]

Technical solution

[0014] In an embodiment, a method performed by a terminal in a wireless communication system is provided. The method includes: receiving configuration information about a set of one or more numbers of physical uplink control channel (PUCCH) repetitions from a base station; receiving downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH) from the base station; receiving PDSCH from the base station based on the DCI; determining a plurality of time slots for PUCCH repetition based on the configuration information when the set of one or more numbers includes a single value or based on the configuration information and the DCI when the set of one or more numbers includes more than one value; and transmitting a PUCCH including hybrid automatic repeat request acknowledgment (HARQ-ACK) information for the PDSCH to the base station on the determined plurality of time slots.

[0015] In an embodiment, a method performed by a base station in a wireless communication system is provided. The method includes: transmitting configuration information about a set of one or more numbers of PUCCH repetitions; transmitting a DCI for scheduling a PDSCH to a terminal; transmitting a PDSCH to the terminal according to the DCI; and receiving a PUCCH including HARQ-ACK information for the PDSCH from the terminal on multiple time slots for PUCCH repetition according to the configuration information when the set of one or more numbers includes a single value or according to the configuration information and the DCI when the set of one or more numbers includes more than one value.

[0016] In an embodiment, a terminal in a wireless communication system is provided. The terminal includes a transceiver and a controller. The controller is configured to: receive configuration information about a set of one or more numbers of PUCCH repetitions from a base station via the transceiver; receive DCI for scheduling PDSCH from the base station via the transceiver; receive PDSCH from the base station via the transceiver based on the DCI; determine multiple time slots for PUCCH repetition based on the configuration information when the set of one or more numbers includes a single value or based on the configuration information and the DCI when the set of one or more numbers includes more than one value; and transmit PUCCH including HARQ-ACK information for PDSCH to the base station via the transceiver on the determined multiple time slots.

[0017] In an embodiment, a base station in a wireless communication system is provided. The base station includes a transceiver and a controller. The controller is configured to: transmit configuration information about a set of one or more numbers of PUCCH repetitions via the transceiver; transmit a DCI for scheduling a PDSCH to a terminal via the transceiver; transmit the PDSCH to the terminal via the transceiver according to the DCI; and receive a PUCCH including HARQ-ACK information for the PDSCH from the terminal via the transceiver on multiple time slots for PUCCH repetition according to the configuration information when the set of one or more numbers includes a single value or according to the configuration information and the DCI when the set of one or more numbers includes more than one value.

[0018] [Beneficial effects of the invention]

[0019] According to the embodiments of the present disclosure, services can be efficiently provided in a wireless communication system such as a satellite communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0021] Figure 1 The basic structure of the time-frequency domain according to an embodiment of the present disclosure is shown, where the time-frequency domain is a radio resource region in which the NR system transmits data or control channels in a downlink or uplink;

[0022] Figure 2 The synchronization signal (SS) and physical broadcast channel (PBCH) of the NR system mapped in the frequency domain and the time domain according to an embodiment of the present disclosure are shown;

[0023] Figure 3 shows symbols through which SS / PBCH blocks may be transmitted according to subcarrier spacing according to an embodiment of the present disclosure;

[0024] Figure 4 An example of a control resource set (CORESET) for transmitting a downlink control channel in a 5G wireless communication system according to an embodiment of the present disclosure is shown;

[0025] Figure 5 An example of a message transmitted from a MAC layer to a physical layer in a downlink in a communication system according to an embodiment of the present disclosure is shown;

[0026] Figure 6 An example of a message transmitted from a MAC layer to a physical layer in an uplink in a communication system according to an embodiment of the present disclosure is shown;

[0027] Figure 7 An example of a process in which one transport block (TB) is divided into several code blocks (CBs) and a CRC is added according to an embodiment of the present disclosure is shown;

[0028] Figure 8 The present invention shows a processing time of a terminal according to a timing advance when the terminal receives a first signal and transmits a second signal in response to the first signal in a 5G or NR system according to an embodiment of the present disclosure;

[0029] Fig. 9 An example of scheduling and transmitting data (e.g., TB) according to a time slot, receiving HARQ-ACK feedback for the data, and performing retransmission according to the feedback according to an embodiment of the present disclosure is shown;

[0030] Fig.10 An example of a communication system using a satellite according to an embodiment of the present disclosure is shown;

[0031] Fig.11 The earth orbit period of a communication satellite according to an embodiment of the present disclosure is shown according to the altitude and height of the satellite;

[0032] Fig.12 Satellite-to-terminal direct communication according to an embodiment of the present disclosure is shown;

[0033] Fig.13 The use scenario of satellite-to-terminal direct communication according to an embodiment of the present disclosure is shown;

[0034] Fig.14 An example of calculating the expected data throughput in an uplink when a LEO satellite at an altitude of 1200 km and a terminal on the ground perform direct communication according to an embodiment of the present disclosure is shown;

[0035] Fig.15An example of calculating the expected data throughput in an uplink when a GEO satellite at an altitude of 35,786 km and a terminal on the ground perform direct communication according to an embodiment of the present disclosure is shown;

[0036] Fig.16 The path loss value between a terminal and a satellite according to a path loss model and the path loss between a terminal and a ground network communication base station according to a path loss model are shown according to an embodiment of the present disclosure;

[0037] Fig.17 The altitude and position of a satellite according to an embodiment of the present disclosure, and a formula and result for calculating the amount of Doppler shift experienced by a signal transmitted from a satellite according to the position of a ground user when the signal is received by the ground user;

[0038] Fig.18 shows the velocity of a satellite calculated from the altitude of the satellite according to an embodiment of the present disclosure;

[0039] Fig.19 shows the Doppler shift experienced by different terminals within a beam transmitted by a satellite to the ground according to an embodiment of the present disclosure;

[0040] Fig. 20 shows the difference in Doppler shift occurring within a beam according to the position of a satellite determined from an elevation angle according to an embodiment of the present disclosure;

[0041] Fig.21 shows the delay time from the terminal to the satellite and the round-trip delay time between the terminal-satellite-base station according to the position of the satellite determined based on the elevation angle according to an embodiment of the present disclosure;

[0042] Fig. 22 shows the maximum difference of the round trip delay time varying according to the user position within one beam according to an embodiment of the present disclosure;

[0043] Fig.23 An example of the information structure of RAR according to an embodiment of the present disclosure is shown;

[0044] Fig.24 An example of the relationship between PRACH preamble configuration resources and RAR reception time in an LTE system according to an embodiment of the present disclosure is shown;

[0045] Fig.25 An example of the relationship between PRACH preamble configuration resources and RAR reception time in a 5G NR system according to an embodiment of the present disclosure is shown;

[0046] Fig.26An example of the timing of downlink frames and uplink frames of a terminal according to an embodiment of the present disclosure is shown;

[0047] Fig. 27 An example of continuous movement of the angle of a satellite at a terminal located on or on the ground surface of the earth as the satellite orbits the earth in a satellite orbit according to an embodiment of the present disclosure is shown;

[0048] Fig.28 An example of the structure of an artificial satellite according to an embodiment of the present disclosure is shown;

[0049] Fig.29 The terminal according to an embodiment of the present disclosure determines N from the initial access TA An example of the process;

[0050] Fig.30 The terminal according to an embodiment of the present disclosure determines N from the initial access TA 、N TA,UE-specific and N TA,common An example of the process;

[0051] Fig.31 Another example of an operation process of a terminal in a communication system according to an embodiment of the present disclosure is shown;

[0052] Fig.32 Another example of an operation process of a terminal in a communication system according to an embodiment of the present disclosure is shown;

[0053] Fig.33 An example of base station operation for reporting a TA value of a terminal according to an embodiment of the present disclosure is shown;

[0054] Fig.34 An example of terminal operation for reporting a TA value of a terminal according to an embodiment of the present disclosure is shown;

[0055] Fig.35 An example showing the difference in propagation delay time between a terrestrial network and a satellite network according to an embodiment of the present disclosure;

[0056] Fig.36 A flow chart showing a terminal accessing a satellite network according to an embodiment of the present disclosure is shown;

[0057] Fig.37 An initial access process according to an embodiment of the present disclosure is shown;

[0058] Fig.38 A flowchart showing the operation of a terminal performing repeated PUCCH transmission including HARQ-ACK information for message 4 PDSCH according to an embodiment of the present disclosure is shown;

[0059] Fig.39 shows the internal structure of a terminal according to an embodiment of the present disclosure;

[0060] Fig.40 shows the internal structure of a satellite according to an embodiment of the present disclosure;

[0061] Fig.41 shows the internal structure of a base station according to an embodiment of the present disclosure; and

[0062] Fig.42 Various frequency hopping methods according to embodiments of the present disclosure are shown. DETAILED DESCRIPTION

[0063] Before proceeding to the following detailed description, it may be helpful to set forth definitions of certain words and phrases used throughout this patent document: the term "including" and its derivatives mean including but not limited to; the term "or" is inclusive, meaning and / or; the phrases "associated with" and "associated with" and their derivatives may mean including, included within, interconnected with, containing, contained within, connected to or connected with, coupled to or coupled with, capable of communicating with, cooperating with, interleaved, juxtaposed, proximate to, bound to or bound with, having, having the property of, and the like; and the term "controller" means any device, system, or part thereof that controls at least one operation, which device may be implemented in hardware, firmware, or software, or some combination of at least two thereof. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether local or remote.

[0064] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embedded in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, steps, functions, objects, classes, instances, related data or a part thereof suitable for being implemented with a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disc (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media excludes wired, wireless, optical or other communication links that transmit instantaneous electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data, and media that can store data and then rewrite data, such as rewritable optical discs or erasable memory devices.

[0065] Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0066] Discussed below Figures 1 to 42 The various embodiments used to describe the principles of the present disclosure in this patent document are only for illustration and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0067] The new air interface (NR) access technology, which is a new 5G communication technology, is being designed to allow various services to be freely multiplexed in time and frequency resources, and therefore, waveforms / parameter sets, etc. and reference signals can be dynamically or freely allocated according to the needs of the service. In order to provide the best service to the terminal in wireless communication, data transmission optimized by measuring channel quality and interference amount is important, and therefore, accurate measurement of channel status is necessary. However, unlike 4G communication where channel and interference characteristics do not change significantly according to frequency resources, in the case of 5G channels, channel and interference characteristics vary greatly according to services, so subset support at the frequency resource group (FRG) level is required to divide and measure channel and interference characteristics. On the other hand, in the NR system, the types of services supported can be divided into categories such as enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). eMBB can be a service targeting high-speed data transmission of large-capacity data, mMTC can be a service targeting minimizing terminal power and accessing multiple terminals, and URLLC can be a service targeting high reliability and low latency. Depending on the type of service applied to the terminal, different requirements may apply.

[0068] In this way, a variety of services can be provided to users in a communication system, and a method of providing each service matching its characteristics within the same period of time and an apparatus using the method are required to provide such a variety of services to users.

[0069] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0070] In the process of describing the embodiments of the present disclosure, descriptions related to technical contents well-known in the art and not directly related to the present disclosure will be omitted. Such unnecessary descriptions are omitted to prevent the main idea of ​​the present disclosure from being obscured and to convey the main idea more clearly.

[0071] For the same reason, in the accompanying drawings, some elements may be exaggerated, omitted or schematically shown. In addition, the size of each element does not fully reflect the actual size. In the accompanying drawings, the same or corresponding elements have the same reference numerals.

[0072] By reference to the embodiments described in detail below in conjunction with the accompanying drawings, the advantages and features of the present disclosure and their implementation will be apparent. However, the present disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose the present disclosure and inform those skilled in the art of the scope of the present disclosure, and the present disclosure is limited only by the scope of the attached claims. Throughout the entire specification, the same or similar reference numerals represent the same or similar elements.

[0073] In this article, it should be understood that each frame of the flowchart diagram and the frame combination in the flowchart diagram can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device create a device for realizing the function specified in one or more flowchart frames. These computer program instructions can also be stored in a computer-available or computer-readable memory, which can instruct the computer or other programmable data processing device to operate in a particular manner, so that the instructions stored in the computer-available or computer-readable memory produce an article including an instruction device, which implements the function specified in the one or more flowchart frames. The computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are performed on a computer or other programmable device, thereby generating a computer-implemented process, so that the instructions executed on a computer or other programmable device provide steps for realizing the function specified in one or more flowchart frames.

[0074] In addition, each box of the flowchart diagram can represent a module, a code segment or a code portion, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the box may not occur in order. For example, depending on the functionality involved, two boxes shown in succession can actually be executed roughly at the same time, or these boxes can sometimes be executed in reverse order.

[0075] As used in the embodiments of the present disclosure, "unit" refers to a software element or hardware element that performs a predetermined function, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). However, "unit" does not always have the meaning of being limited to software or hardware. "Unit" can be constructed to be stored in an addressable storage medium or to execute one or more processors. Therefore, "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and parameters. The elements and functions provided by "unit" can be combined into a smaller number of elements or "units", or divided into a larger number of elements or "units". In addition, elements and "units" can be implemented to reproduce one or more CPUs in a device or a secure multimedia card. In addition, the "unit" in the embodiment can include one or more processors.

[0076] Wireless communication systems are developing into broadband wireless communication systems to provide high-speed and high-quality packet data services as well as typical voice-based services using communication standards such as 3GPP's High Speed ​​Packet Access (HSPA), LTE {Long Term Evolution or Evolved Universal Terrestrial Radio Access (E-UTRA)}, Advanced LTE (LTE-A), LTE-Pro, 3GPP2's High Speed ​​Packet Data (HRPD), Ultra Mobile Broadband (UMB), IEEE 802.16e, etc. In addition, as a fifth-generation wireless communication system, 5G or New Radio (NR) standards are being developed.

[0077] As a typical example of a broadband wireless communication system, the NR system adopts an orthogonal frequency division multiplexing (OFDM) scheme in the downlink (DL) and uplink (UL). More specifically, the NR system adopts a cyclic prefix OFDM (CP-OFDM) scheme in the downlink and two schemes in the uplink, namely, a CP-OFDM scheme and a discrete Fourier transform spread (DFT-S-OFDM) scheme. The uplink indicates a radio link through which a user equipment (UE) or a mobile station (MS) transmits data or a control signal to a base station (BS) or (gNode B), and the downlink indicates a radio link through which a base station transmits data or a control signal to a UE. The above multiple access schemes separate the data or control information of the corresponding users by allocating and operating time-frequency resources to transmit the data or control information of each user so as to avoid overlapping with each other (that is, to establish orthogonality).

[0078] The NR system adopts a hybrid automatic repeat request (HARQ) scheme, in which the corresponding data is retransmitted in the physical layer when decoding is unsuccessful at the time of initial transmission. In the HARQ scheme, when the receiver fails to accurately decode the data, the receiver transmits information (negative acknowledgment: NACK) notifying the transmitter of unsuccessful decoding, and thus the transmitter can retransmit the corresponding data at the physical layer. The receiver can improve data reception performance by combining the data retransmitted by the transmitter with the data that failed to be decoded previously. In addition, when the receiver accurately decodes the data, the receiver transmits information (acknowledgement: ACK) notifying the transmitter of successful decoding, and thus the transmitter can transmit new data.

[0079] According to an embodiment of the present disclosure, when a terminal attempts to connect to a base station via a satellite, a long delay time occurs in the arrival of radio waves due to the long distance of hundreds of kilometers, thousands of kilometers or more between the terminal and the satellite and between the satellite and the base station on the ground. The delay time between the terminal, the satellite and the base station is much longer than when the terminal and the base station communicate directly in a ground network. In addition, since the satellite is constantly moving, the delay time between the terminal, the satellite and the base station changes over time.

[0080] Therefore, when a terminal transmits a signal to and receives a signal from a base station via a satellite, the present disclosure provides a method and apparatus in which the base station indicates a time offset and the terminal corrects the time offset based on a time-varying delay time that occurs according to a long distance from the satellite and the movement of the satellite. In addition, the terminal can calculate a portion of the time offset based on the satellite and its own position and time information, and provides a method and apparatus for applying the calculated portion of the time offset and reporting it to the base station.

[0081] That is, according to an embodiment of the present disclosure, when a terminal transmits a signal to a base station and receives a signal from a base station via a satellite, it may be necessary to correct a time offset due to a long distance between the terminal and the satellite. Therefore, the present disclosure provides a method and an apparatus, in which a base station indicates time offset information to a terminal, the terminal calculates and applies a portion of a timing advance, the terminal reports the timing advance information to the base station, and the terminal uses the information indicated by the base station to correct the time offset.

[0082] As described above, by using the present disclosure, a terminal can access a base station through a satellite, the base station indicates a time offset to the terminal, and the terminal calculates and corrects the time offset, thereby effectively exchanging signals between the base station and the terminal.

[0083] Figure 1 The basic structure of the time-frequency domain according to an embodiment of the present disclosure is shown, where the time-frequency domain is a radio resource region in which the NR system transmits data or control channels in the downlink or uplink.

[0084] exist Figure 1 , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is the OFDM symbol, and Nsymb OFDM symbols 102 are aggregated to configure a time slot 106. The length of a subframe may be defined as 1.0 ms, and a radio frame 114 may be defined as 10 ms. The smallest transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth consists of a total of NBW subcarriers 104. A frame may be defined as 10 ms. A subframe may be defined as 1 ms, and thus a frame may consist of a total of 10 subframes. A time slot may be defined as 14 OFDM symbols (i.e., the number of symbols per time slot). =14). A subframe may consist of one or more time slots, and the number of time slots per subframe may vary according to μ, which is a configured value of the subcarrier spacing. When μ=0, a subframe may consist of one time slot, and when μ=1, a subframe may consist of two time slots. That is, the number of time slots per subframe is The number of time slots per frame can vary depending on the configured value μ of the subcarrier spacing and, therefore, the number of time slots per frame Can be changed. According to each subcarrier spacing configuration μ and It can be defined in Table 1 below.

[0085]

Table 1

[0086]

[0087] The terminal before the radio resource control (RRC) connection can receive the initial bandwidth part (initial BWP) for initial access from the base station through the master information block (MIB). More specifically, at the time of initial access, the terminal can receive the configuration information about the control resource set (CORESET) and the search space of the physical downlink control channel (PDCCH) through which the system information required for initial access (remaining system information; RMSI or system information block 1; which can correspond to SIB) can be transmitted. The control resource set and the search space configured by the MIB can each be regarded as an identifier (ID) 0. The base station can notify the terminal of the configuration information such as the frequency allocation information, time allocation information and parameter set of the control resource set #0 through the MIB. In addition, the base station can notify the terminal of the configuration information about the monitoring period and timing of the control resource set #0, that is, the configuration information about the search space #0 through the MIB. The terminal can regard the frequency domain range configured as the control resource set #0 obtained from the MIB as the initial bandwidth part for initial access. In this case, the identifier (ID) of the initial bandwidth part can be regarded as 0.

[0088] The MIB may include information such as the following Table 2. Of course, this is not limited to the following example.

[0089]

Table 2

[0090]

[0091] The descriptions of the MIB fields are as follows.

[0092] -cellBarred:

[0093] The value barred means that the cell is barred, as defined in TS 38.304.

[0094] -dmrs-TypeA-Position:

[0095] Position of the (first) DM-RS for downlink (see TS 38.211) and uplink (see TS 38.211)

[0096] -intraFreqReselection:

[0097] When the highest ranked cell is barred or considered barred by the UE, control cell selection / reselection to intra-frequency cells as specified in TS 38.304.

[0098] -pdcch-ConfigSIB1:

[0099] Determine the common ControlResourceSet (CORESET), common search space and necessary PDCCH parameters. If the field ssb-SubcarrierOffset indicates that SIB1 does not exist, the field pdcch-ConfigSIB1 indicates the frequency position where the UE can find the SS / PBCH block with SIB1 or the frequency range where the network does not provide the SS / PBCH block with SIB1 (see TS38.213).

[0100] -ssb-SubcarrierOffset:

[0101] Corresponds to kSSB which is the frequency domain offset in number of subcarriers between the SSB and the total resource block grid (see TS 38.213). (See TS 38.211).

[0102] The value range of this field may be extended by additional most significant bits encoded within the PBCH, as specified in TS 38.213.

[0103] This field may indicate that the cell does not provide SIB1 and therefore CORESET#0 is not configured in the MIB (see TS 38.213). In this case, the field pdcch-ConfigSIB1 may indicate the frequency location where the UE may (cannot) find the SS / PBCH with the control resource set and search space of SIB1 (see TS 38.213).

[0104] -subCarrierSpacingCommon:

[0105] Subcarrier spacing used for SIB1, Msg.2 / 4 for initial access, paging and broadcast SI-messages. If the UE acquires this MIB on FR1 carrier frequency, the value scs15or60 corresponds to 15 kHz and the value scs30or120 corresponds to 30 kHz. If the UE acquires this MIB on FR2 carrier frequency, the value scs15or60 corresponds to 60 kHz and the value scs30or120 corresponds to 120 kHz.

[0106] -systemFrameNumber:

[0107] The 6 most significant bits (MSBs) of the 10-bit System Frame Number (SFN). The 4 LSBs of the SFN are transmitted in the PBCH transport block as part of the channel coding (ie, outside the MIB coding), as defined in TS 38.212.

[0108] In the method for configuring the bandwidth part, the terminal before the RRC connection can receive configuration information about the initial bandwidth part through the MIB at the time of initial access. More specifically, the terminal can receive the configuration of the control resource set for the downlink control channel, through which the downlink control information (DCI) for scheduling SIB can be transmitted from the MIB of the physical broadcast channel (PBCH). In this case, the bandwidth of the control resource set configured as the MIB can be regarded as the initial bandwidth part, and through the configured initial bandwidth part, the terminal can receive the physical downlink shared channel (PDSCH) through which the SIB is transmitted. In addition to receiving SIB, the initial bandwidth part can also be used for other system information (OSI), paging and random access.

[0109] When one or more bandwidth parts are configured for the terminal, the base station may instruct the terminal to change the bandwidth part by using the bandwidth part indicator field in the DCI.

[0110] The basic unit of resources in the time-frequency domain is a resource element (RE) 112, which can be expressed as an OFDM symbol index and a subcarrier index. A resource block (RB) (or physical resource block; PRB) 108 is defined as NRB consecutive subcarriers 110 in the frequency domain. In general, the minimum transmission unit of data can be an RB unit. In an NR system, Nsymb=14 and NRB=12, and the NBW can be proportional to the bandwidth of the system transmit band. The data rate can increase in proportion to the number of RBs scheduled to the terminal.

[0111] In the NR system, in the case of an FDD system that operates by dividing the downlink and uplink by frequency, the downlink transmission bandwidth and the uplink transmission bandwidth may be different from each other. The channel bandwidth represents the RF bandwidth corresponding to the system transmission bandwidth. Tables 3 and 4 show some of the correspondences between the system transmission bandwidth, subcarrier spacing, and channel bandwidth defined in the NR system in a frequency range 1 (FR 1) below 6 GHz and a frequency range (FR2) above 6 GHz, respectively. For example, an NR system with a 100 MHz channel bandwidth and a 30 kHz subcarrier width has a transmission bandwidth of 273 RBs. In the following, N / A may be a bandwidth-subcarrier combination that is not supported by the NR system.

[0112]

Table 3

[0113]

[0114]

Table 4

[0115]

[0116] In the NR system, the frequency range may be divided into FR1 and FR2 and defined as shown in Table 5 below.

[0117]

Table 5

[0118] Frequency range name Corresponding frequency range FR1 450MHz to 7125MHz FR2 24250MHz to 52600MHz

[0119] Of course, the ranges of FR1 and FR2 described above may be variously changed and applied. As an example, the frequency range of FR1 may be changed and applied from 450 MHz to 6,000 MHz.

[0120] Next, the synchronization signal (SS) / PBCH block in 5G will be described.

[0121] The SS / PBCH block may refer to a physical layer channel block composed of PSS (Primary SS, Primary Synchronization Signal), SSS (Secondary SS, Sub-Synchronization Signal) and PBCH. Specifically, they are as follows.

[0122] -PSS: A signal used as a standard for downlink time / frequency synchronization and can provide some information about the cell ID.

[0123] -SSS: A signal used as a standard for downlink time / frequency synchronization and can provide the remaining cell ID information not provided by PSS. In addition, it can be used as a reference signal for demodulation of PBCH.

[0124] -PBCH: can provide basic system information necessary for transmitting and receiving data channels and control channels of terminals. Basic system information may include search space related control information indicating radio resource mapping information of control channels, scheduling control information of separate data channels for transmitting system information, etc.

[0125] -SS / PBCH block: An SS / PBCH block may consist of a combination of PSS, SSS, and PBCH. One or more SS / PBCH blocks may be transmitted within 5 ms, and each transmitted SS / PBCH block may be distinguished by an index.

[0126] The terminal can detect the PSS and SSS and decode the PBCH at the time of initial access. The terminal can obtain the MIB from the PBCH and can receive the configuration of the control resource set #0 (which can correspond to the control resource set in which the control resource set index is 0) through the MIB. Assuming that the selected SS / PBCH block and the demodulation reference signal (DMRS) transmitted in the control resource set #0 are QCLed (quasi-co-located), the terminal can perform monitoring on the control resource set #0. The terminal can receive system information through the downlink control information transmitted from the control resource set #0. The terminal can obtain the random access channel (RACH) related configuration information necessary for initial access from the received system information. Considering the selected SS / PBCH index, the terminal can transmit a physical RACH (PRACH) to the base station, and the base station receiving the PRACH can obtain information about the SS / PBCH block index selected by the terminal. Through this process, the base station can know which block the terminal has selected in each SS / PBCH block and monitor the control resource set #0 associated with the selected block.

[0127] Figure 2 The synchronization signal (SS) and physical broadcast channel (PBCH) of the NR system mapped in the frequency domain and the time domain according to an embodiment of the present disclosure are shown.

[0128] A primary synchronization signal (PSS) 201, a secondary synchronization signal (SSS) 203, and a PBCH are mapped to 4 OFDM symbols, the PSS and the SSS are mapped to 12 RBs, and the PBCH is mapped to 20 RBs. Figure 2The table in shows how the frequency range of 20 RBs changes according to the subcarrier spacing (SCS). The resource region in which PSS, SSS, and PBCH are transmitted may be referred to as an SS / PBCH block. In addition, the SS / PBCH block may be referred to as a synchronization signal block (SSB).

[0129] Figure 3 It is shown that symbols through which SS / PBCH blocks can be transmitted according to subcarrier spacing according to an embodiment of the present disclosure.

[0130] refer to Figure 3 , the subcarrier spacing can be configured as 15kHz, 30kHz, 120kHz, 240kHz, etc., and the position of the symbol where the SS / PBCH block (or SSB) can be located can be determined according to each subcarrier spacing. Figure 3 The symbol positions of the SSB symbols can be transmitted in 1 ms according to the subcarrier spacing, and it is not necessary to always Figure 3 The SSB is transmitted in the area shown. The location in which the SSB is transmitted can be configured for the terminal through system information or dedicated signaling.

[0131] Hereinafter, a downlink control channel in a 5G communication system will be described in more detail with reference to the accompanying drawings.

[0132] Figure 4 An example of a control resource set (CORESET) for transmitting a downlink control channel in a 5G wireless communication system according to an embodiment of the present disclosure is shown.

[0133] Figure 4 An example is shown in which a UE bandwidth part 410 is configured on the frequency axis and two control regions (control resource set #1 (401), control resource set #2 (420)) are configured within a time slot 402 on the time axis. Control resource sets 391 and 402 may be configured as specific frequency resources 403 within the entire UE bandwidth part 410 on the frequency axis. One or more OFDM symbols may be configured on the time axis and may be defined as a control resource set duration 404. Figure 4 In the example shown, control resource set #1 (401) is configured as a control resource set duration of two symbols, and control resource set #2 (402) is configured as a control resource set duration of one symbol.

[0134] The control resource set in the above 5G system can be configured for the terminal by the base station through high-level signaling (e.g., system information, MIB, RRC). Configuring a control resource set for a terminal may refer to providing information such as a control resource set identifier (identification), a frequency position of a control resource set, and a symbol length of a control resource set. For example, high-level signaling may include the information in Table 6 below. Of course, it is not limited to the following examples.

[0135]

Table 6

[0136]

[0137]

[0138] In Table 6, the tci-StatesPDCCH (abbreviated as transmission configuration indication (TCI) state) configuration information may include information about one or more SS / PBCH block indices or channel state information reference signal (CSI-RS) indices that have a QCL relationship with the DMRS transmitted in the corresponding control resource set.

[0139] Next, downlink control information (DCI) in the 5G system will be described in detail.

[0140] In the 5G system, scheduling information for an uplink shared channel (or physical uplink shared channel, PUSCH) or a downlink shared channel (or physical downlink shared channel, PDSCH) is transmitted from the base station to the terminal via DCI. The terminal can monitor the DCI format for fallback and the DCI format for non-fallback for PUSCH or PDSCH. The fallback DCI format may consist of fixed fields predefined between the base station and the terminal, and the non-fallback DCI format may include configurable fields. In addition, there are UEs of various formats, and each format may indicate whether each format is a DCI for power control or a DCI for notifying a slot format indicator (SFI).

[0141] DCI can be transmitted via PDCCH (Physical Downlink Control Channel) through a channel coding and modulation process. A cyclic redundancy check (CRC) is attached to the DCI message payload, and the CRC can be scrambled using a radio network temporary identifier (RNTI) corresponding to the identity of the terminal. Different RNTIs can be used depending on the purpose of the DCI message (e.g., UE-specific data transmission, power control command, or random access response). That is, the RNTI is not explicitly transmitted, but is included in the CRC calculation process and transmitted. After receiving the DCI message transmitted on the PDCCH, the terminal identifies the CRC by using the allocated RNTI, and if the CRC identification result is correct, the terminal can recognize that the received DCI message has been transmitted to the terminal. PDCCH can be mapped and transmitted in a control resource set (CORESET) configured for the terminal.

[0142] For example, the DCI for scheduling PDSCH for system information (SI) can be scrambled with SI-RNTI. The DCI for scheduling PDSCH for random access response (RAR) message can be scrambled with RA-RNTI. The DCI for scheduling PDSCH for paging message can be scrambled with P-RNTI. The DCI for notifying slot format indicator (SFI) can be scrambled with SFI-RNTI. The DCI for notifying transmit power control (TPC) can be scrambled with TPC-RNTI. The DCI for scheduling UE-specific PDSCH or PUSCH can be scrambled with cell RNTI (C-RNTI). Of course, the type of RNTI is not limited to the above examples.

[0143] DCI format 0_0 may be used as a fallback DCI for scheduling PUSCH, and in this case, the CRC may be scrambled with the C-RNTI. The DCI format 0_0 in which the CRC is scrambled with the C-RNTI may include information such as shown below. Of course, this is not limited to the following example.

[0144]

Table 7

[0145]

[0146] DCI format 1_0 may be used as a non-fallback DCI for scheduling a PUSCH, and in this case, the CRC may be scrambled with the C-RNTI. The DCI format 0_1 ​​in which the CRC is scrambled with the C-RNTI may include information such as shown below. Of course, this is not limited to the following example.

[0147]

Table 8

[0148]

[0149]

[0150] DCI format 1_0 may be used as a fallback DCI for scheduling PDSCH, and in this case, the CRC may be scrambled with the C-RNTI. The DCI format 1_0 in which the CRC is scrambled with the C-RNTI may include information such as shown below. Of course, this is not limited to the following example.

[0151]

Table 9

[0152]

[0153] DCI format 1_1 may be used as a non-fallback DCI for scheduling PDSCH, and in this case, the CRC may be scrambled with the C-RNTI. The DCI format 1_1 in which the CRC is scrambled with the C-RNTI may include information such as shown below. Of course, this is not limited to the following example.

[0154]

Table 10

[0155]

[0156]

[0157] As an example, each control information included in DCI format 1_1 which is downlink data scheduling control information (DL grant) may include the following information. Of course, this is not limited to the following example.

[0158] - Carrier indicator: Indicates on which carrier the data scheduled by the DCI is transmitted - 0 or 3 bits

[0159] - Identifier of DCI format: Indicates the DCI format, and specifically, is an indicator that distinguishes whether the DCI is for downlink or uplink. - [1] bit.

[0160] - Bandwidth fraction indicator: Indicates when the bandwidth fraction changes - 0, 1 or 2 bits.

[0161] - Frequency domain resource assignment: Resource assignment information indicating frequency domain resource assignment, and the expressed resources vary depending on whether the resource assignment type is 0 or 1.

[0162] - Time domain resource assignment: The resource assignment information indicating the time domain resource assignment may indicate the configuration of the higher layer signaling or the predetermined PDSCH time domain resource assignment list - 1, 2, 3 or 4 bits.

[0163] - VRB to PRB mapping: Indicates the mapping relationship between virtual resource blocks (VRBs) and physical resource blocks (PRBs) - 0 or 1 bit.

[0164] -PRB bundling size indicator: Indicates the physical resource block bundling size assuming the same precoding is applied - 0 or 1 bit.

[0165] - Rate matching indicator: Indicates which rate matching group is applied among the rate matching groups configured as higher layers applied to PDSCH - 0, 1 or 2 bits.

[0166] -ZP CSI-RS trigger: Trigger zero power channel state information reference signal - 0, 1 or 2 bits

[0167] - Configuration information related to a transport block (TB): indicating the modulation and coding scheme (MCS), new data indicator (NDI) and redundancy version (RV) of one or two TBs.

[0168] - Modulation and Coding Scheme (MCS): Indicates the modulation scheme and coding rate used for data transmission. That is, it can indicate the coding rate value, which provides the transport block size (TBS) and channel coding information, and whether the value is QPSK, 16QAM, 64QAM or 256QAM

[0169] - New data indicator: indicates whether it is HARQ initial transmission or retransmission.

[0170] - Redundancy version: indicates the redundancy version of HARQ.

[0171] -HARQ process number: Indicates the HARQ process number applied to PDSCH - 4 bits

[0172] - Downlink assignment index: Index used to generate dynamic HARQ-ACK codebook when reporting HARQ-ACK for PDSCH - 0 or 2 or 4 bits.

[0173] - TPC command for scheduling PUCCH: Power control information of PUCCH applied to HARQ-ACK report for PDSCH - 2 bits.

[0174] -PUCCH resource indicator: Information indicating resources of PUCCH used for HARQ-ACK reporting on PDSCH - 3 bits.

[0175] -PDSCH to HARQ_Feedback Timing Indicator: Configuration information of the PUCCH for HARQ-ACK reporting for PDSCH is transmitted on which time slot - 3 bits.

[0176] - Antenna port: Information indicating the antenna port of the PDSCH DMRS and DMRS CDM group in which the PDSCH is not transmitted - 4, 5, or 6 bits.

[0177] -Transmission configuration indication: Information indicating beam-related information of PDSCH - 0 or 3 bits.

[0178] -SRS request: Information requesting SRS transmission - 2 bits.

[0179] -CBG transmission information: When code block group-based retransmission is configured, information indicating which code block group (CBG) corresponding to the data is transmitted through PDSCH - 0, 2, 4, 6 or 8 bits.

[0180] -CBG clear information: Information indicating whether a code block group previously received by the terminal can be used for HARQ combining - 0 or 1 bit.

[0181] -DMRS sequence initialization: indicates the DMRS sequence initialization parameter - 1 bit.

[0182] Hereinafter, a time domain resource allocation method for a data channel in a 5G communication system will be described.

[0183] Downlink data may be transmitted on PDSCH, i.e., a physical channel for downlink data transmission. Uplink data may be transmitted on PUSCH, i.e., a physical channel for uplink data transmission. PDSCH may be transmitted after the control channel transmission period, and scheduling information such as a specific mapping position in the frequency domain and a modulation method may be determined based on DCI transmitted through PDCCH.

[0184] The base station can configure a table of time domain resource allocation information about the physical downlink shared channel (PDSCH) and the physical uplink shared channel (PUSCH) to the terminal through high-level signaling (e.g., RRC signaling). A table consisting of up to 16 (maxNrofDL-Allocations) entries can be configured for PDSCH, and a table consisting of up to 16 (maxNrofUL-Allocations) entries can be configured for PUSCH. The time domain resource allocation information may include, for example, PDCCH to PDSCH time slot timing (corresponding to the time interval in time slots between the time when the PDCCH is received and the time when the PDSCH scheduled by the received PDCCH is transmitted, represented by K0) or PDCCH to PUSCH time slot timing (corresponding to the time interval in time slots between the time when the PDCCH is received and the time when the PUSCH scheduled by the received PDCCH is transmitted, represented by K2), information about the position and length of the starting symbol of the PDSCH or PUSCH scheduled in the time slot, the mapping type of the PDSCH or PUSCH, etc. For example, information such as the following Table 11 and Table 12 may be notified from the base station to the terminal. Of course, this is not limited to the following example.

[0185]

Table 11

[0186]

[0187]

Table 12

[0188]

[0189] The base station may notify the terminal of one of the entries in the table of time domain resource allocation information through L1 signaling (e.g., DCI) (e.g., the base station may indicate it with the "time domain resource allocation" field in the DCI). The terminal may obtain the time domain resource allocation information about the PDSCH or PUSCH based on the DCI received from the base station.

[0190] According to an embodiment of the present disclosure, time domain resource assignment may be transmitted by information about the time slot in which the PDSCH / PUSCH is transmitted, the starting symbol position in the time slot, and the number of symbols L to which the PDSCH / PUSCH is mapped. In the above, S may be a relative position from the beginning of the time slot, L may be the number of consecutive symbols, and S and L may be determined from a start and length indicator value (SLIV) defined as the following equation (1).

[0191] [Equation 1]

[0192] If (L-1)≤7, then

[0193] SLIV 14·(L-1)+S

[0194] otherwise,

[0195] SLIV=14·(14-L+1)+(14-1-S)

[0196] Where 0 <L≤14-S

[0197] In the NR system, the PDSCH mapping type is defined as type A and type B. In PDSCH mapping type A, the first of the DMRS symbols is located in the second or third OFDM symbol of the time slot. In PUSCH mapping type B, the first symbol of the DMRS OFDM symbol of the first OFDM symbol in the time domain resources allocated by PUSCH transmission is located.

[0198] The base station notifies the terminal of the modulation method applied to the PDSCH to be transmitted and the size of the data to be transmitted (transport block size (TBS)) through the modulation coding scheme (MCS) in the control information constituting the DCI. According to one embodiment of the present disclosure, the MCS may be composed of 5 bits or more or less. The TBS may correspond to the size before the channel coding for error correction is applied to the data (transport block, TB) that the base station wants to transmit.

[0199] In the present disclosure, a transport block (TB) may include a media access control (MAC) header, a MAC control element, one or more MAC service data units, and padding bits. Alternatively, a TB may refer to a data unit delivered from the MAC layer to the physical layer, or a MAC protocol data unit (PDU).

[0200] Modulation methods supported by the NR system are quadrature phase shift keying (QPSK), quadrature amplitude modulation (16QAM), 64QAM, and 256QAM, where each modulation order (Qm) corresponds to 2, 4, 6, and 8. That is, for QPSK modulation, 2 bits per symbol can be transmitted, for 16QAM modulation, 4 bits per symbol can be transmitted, for 64QAM modulation, 6 bits per symbol can be transmitted, and for 256QAM modulation, 8 bits per symbol can be transmitted.

[0201] The terms physical channel and signal in the NR system may be used to describe the methods and apparatuses provided in the embodiments of the present disclosure. However, the content of the present disclosure may be applied to wireless communication systems other than the NR system.

[0202] In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station.

[0203] In the present disclosure, the conventional terms physical channel and signal may be used interchangeably with data or control signal. For example, PDSCH is a physical channel through which data is transmitted, but in the present disclosure, PDSCH may be referred to as data.

[0204] Hereinafter, in the present disclosure, high-layer signaling is a signal transmission method of transmitting a signal from a base station to a terminal by using a downlink data channel of a physical layer or transmitting a signal from a terminal to a base station by using an uplink data channel of a physical layer, and may be referred to as RRC signaling or a MAC control element (MAC CE).

[0205] According to an embodiment of the present disclosure, a timing advance (TA) may be transmitted through a MAC control element (CE) such as a timing advance command MAC CE or an absolute timing advance command MAC CE.

[0206] On the other hand, a message (e.g., MAC PDU) transmitted from the MAC layer to the physical layer may include one or more MAC sub-PDUs. Each MAC sub-PDU may include one of the following. Of course, this is not limited to the following examples:

[0207] - MAC subheader only (including padding);

[0208] -MAC subheader and MAC SDU;

[0209] -MAC subheader and MAC CE; and / or

[0210] -MAC subheader and padding.

[0211] The MAC SDU may have a variable size, and each MAC subheader may correspond to a MAC SDU, a MAC CE, or padding.

[0212] On the other hand, the message (e.g., MAC PDU) transmitted from the MAC layer to the physical layer can be respectively as follows: Figure 5 and Figure 6 Shown is configured for downlink and uplink.

[0213] First, refer to Figure 5 , an example of a message transmitted from a MAC layer to a physical layer in a downlink in a communication system according to various embodiments of the present disclosure will be described.

[0214] Figure 5 An example of a message transmitted from a MAC layer to a physical layer in a downlink in a communication system according to an embodiment of the present disclosure is shown.

[0215] refer to Figure 5 An example of a message transmitted from the MAC layer to the physical layer in a downlink may be a downlink MAC PDU (DL MAC PDU). Figure 5 , a MAC sub-PDU 500 including a MAC CE 1 may include an R / LCID sub-header 502 and a fixed-size MAC CE 504, and a MAC sub-PDU 510 including a MAC CE 2 may include an R / F / LCID / L sub-header 512 and a variable-size MAC CE 514. In addition, a MAC sub-PDU 520 including a MAC SDU may include an R / F / LCID / L sub-header 522 and a MAC SDU 524.

[0216] exist Figure 5 In the LCID field, LCID represents a logical channel ID field, and the LCID field indicates an instance of a corresponding MAC SDU or a type or padding of a corresponding MAC CE, which is described in detail in the following Tables 13 and 14. Here, the following Table 13 shows the LCID value of DL-SCH, and Table 14 shows the LCID value of UL-SCH.

[0217]

Table 13

[0218]

[0219]

[0220]

Table 14

[0221]

[0222] Each MAC subheader has one LCID field, and the size of the LCID field is 6 bits. For example, when the LCID field is configured as "34", there is one additional octet in the MAC subheader including the eLCID field, and the octet follows the octet including the LCID field. For example, when the LCID field is configured as "33", there are two additional octets in the MAC subheader including the eLCID field, and the two octets follow the octet including the LCID field.

[0223] In addition, eLCID represents an extended logical channel ID field and indicates a logical channel instance of a corresponding MAC SDU or a type of a corresponding MAC CE. The size of the eLCID field is 8 bits or 16 bits.

[0224] In addition, L represents a length field, and the length field indicates the length of the corresponding MAC SDU or variable-size MAC CE. Each MAC subheader has one length field, excluding a subheader corresponding to a MAC SDU including a fixed-size MAC CE, padding, or UL common control channel (CCCH). The size of the length field is indicated by the F field.

[0225] In addition, F represents the format field and indicates the size of the length field. Each MAC subheader has an F field, excluding the MAC SDU including fixed MAC CE, padding, and UL CCCH. The size of the F field is 1 bit, for example, a value of 0 indicates that the length field is 8 bits, and as another example, a value of 1 indicates that the length field is 16 bits.

[0226] In addition, R is a reserved bit and, as an example, is configured to "0".

[0227] like Figure 5 As shown, MAC CE (e.g., MAC CE 1 and MAC CE 2) are placed together, and the MAC sub-PDU including the MAC CE is placed before the MAC sub-PDU including the MAC SDU and the MAC sub-PDU including the padding. Here, the size of the padding can be zero.

[0228] Next, refer to Figure 6 , an example of a message transmitted from a MAC layer to a physical layer in an uplink in a communication system according to various embodiments of the present disclosure will be described.

[0229] Figure 6 An example of a message transmitted from a MAC layer to a physical layer in an uplink in a communication system according to an embodiment of the present disclosure is shown.

[0230] refer to Figure 6An example of a message transmitted from the MAC layer to the physical layer in the uplink may be an uplink MAC PDU (UL MAC PDU). Figure 6 , a MAC sub-PDU 610 including a MAC CE 1 may include an R / LCID sub-header 612 and a fixed-size MAC CE 614, and a MAC sub-PDU 620 including a MAC CE 2 may include an R / F / LCID / L sub-header 622 and a variable-size MAC CE 624. In addition, a MAC sub-PDU 600 including a MAC SDU may include an R / F / LCID / L sub-header 602 and a MAC SDU 604.

[0231] like Figure 6 As shown, MAC CE (e.g., MAC CE 1 and MAC CE 2) are placed together, and the MAC sub-PDU including the MAC CE is placed after the MAC sub-PDU including the MAC SDU and before the MAC sub-PDU including the padding. Here, the size of the padding can be zero.

[0232] exist Figure 5 and Figure 6 In the subheader of the MAC layer, the LCID (i.e., logical channel ID or extended logical channel ID (eLCID)) included in the subheader of the MAC layer may indicate the type of MAC SDU or MAC CE to be transmitted. For example, the mapping of the index of the LCID and the type of the MAC SDU or MAC CE may be as shown in Table 13, and the index of the eLCID and the type of the MAC SDU or MAC CE may be as shown in Table 14. In various embodiments of the present disclosure, the LCID may indicate an instance of a logical channel of a MAC SDU, a type of MAC CE, or padding information of a downlink shared channel (DL-SCH) and an uplink shared channel (UL-SCH). Each MAC subheader maps one LCID, and, for example, the LCID may be implemented with 6 bits.

[0233] Figure 7 An example of a process in which one transport block (TB) is divided into several code blocks (CBs) and a CRC is added according to an embodiment of the present disclosure is shown.

[0234] refer to Figure 7, CRC 703 can be added to the last part or the first part of a transport block (TB) 701 to be transmitted in the uplink or downlink. CRC 703 can have 16 bits or 25 bits, a pre-fixed number of bits, or a variable number of bits depending on channel conditions, etc., and can be used to determine whether channel coding is successful. The block to which CRC 703 is added to TB 701 can be divided into several code blocks (CB) 707, 709, 711 and 713 (705). According to an embodiment of the present disclosure, the code blocks can be divided according to a predetermined maximum size, and in this case, the last code block 713 may be smaller than other code blocks 707, 709 and 711. However, it is not limited to the above example, and the length of the last code block 713 and other code blocks 707, 709 and 711 can be made the same by inserting 0, a random value or 1 into the last code block 713.

[0235] In addition, CRC 717, 719, 721, and 723 may be added to code blocks 707, 709, 711, and 713, respectively (715). CRC may have 16 bits, 24 bits, or a pre-fixed number of bits, and may be used to determine whether channel coding is successful.

[0236] TB 701 and a cyclic generator polynomial can be used to generate CRC 703, and the cyclic generator polynomial can be defined in various formats. For example, when assuming that the cyclic generator polynomial gCRC24A(D)=D24+D23+D18+D17+D14+D11+D10+D7+D6+D5+D4+D3+D+1 and L=24, for TB data a0, a1, a2, a3, ..., aA-1, CRC p0, p1, p2, p3, ..., pL-1 is a value where a0DA+23+a1DA+22+ ...+aA-1D24+p0D23+p1D22+ ...+p22D1+p23 is divided by gCRC24A(D) and the remainder is 0, and p0, p1, p2, p3, ..., pL-1 can be determined. In the above example, it is assumed that the CRC length L is 24, but the CRC length L may be determined as various lengths such as 12, 16, 24, 32, 40, 48, and 64.

[0237] After the CRC is added to the TB by this process, the TB+CRC can be divided into N CBs 707, 709, 711, and 713. CRCs 717, 719, 721, and 723 can be added to the divided CBs 707, 709, 711, and 713 (715). The CRC added to the CB can have a different length than when the CRC added to the TB is generated, or a different cyclic generator polynomial can be used to generate the CRC. In addition, depending on the type of channel code to be applied to the code block, the CRC 703 added to the TB and the CRCs 717, 719, 721, and 723 added to the code block can be omitted. For example, when a low-density parity check (LDPC) code is applied to the code block instead of a turbo code, the CRCs 717, 719, 721, and 723 to be inserted for each code block can be omitted.

[0238] However, even when LDPC is applied, CRC 717, 719, 721, and 723 may be added to the code block. In addition, even when polar codes are used, CRC may be added or omitted.

[0239] As mentioned above Figure 7 As described in, the maximum length of a code block of a TB to be transmitted may be determined according to the type of channel coding applied, and the TB and the CRC added to the TB may be divided into code blocks according to the minimum length of the code block.

[0240] In a conventional LTE system, a CRC of a CB is added to the divided CB, and data bits and CRC of the CB are encoded with a channel code to determine coded bits, and the number of rate matching bits is determined for each coded bit as prearranged.

[0241] In the NR system, the TB size (TBS) can be calculated by the following steps:

[0242] Step 1: Calculate N'RE, which is the number of REs allocated to PDSCH mapping in one PRB within the allocated resources. N'RE can be calculated as here, is 12, and The number of OFDM symbols allocated to the PDSCH may be indicated. It is the number of REs occupied by DMRS of the same code division multiplexing (CDM) group in one physical resource block (PRB). It is the number of REs occupied by the overhead configured as high-layer signaling within a PRB, and can be configured as one of 0, 6, 12 or 18. After that, the total number of REs NRE allocated to PDSCH can be calculated. NRE is calculated as min(156,N'RE)·nPRB, where nPRB represents the number of PRBs allocated to the terminal.

[0243] Step 2: The number of temporary information bits Ninfo can be calculated as NRE*R*Qm*v. Here, R is the code rate, Qm is the modulation order, and information about the value can be transmitted by using the DCI MCS bit field and a pre-arranged table. In addition, v is the number of allocated layers. If Ninfo≤3824, TBS can be calculated by the following step 3. Otherwise, TBS can be calculated by step 4.

[0244] Step 3: You can use the formula and To calculate N'info. TBS can be determined as the value closest to N'info among the values ​​not less than N'info in Table 15 below.

[0245]

Table 15

[0246]

[0247]

[0248] Step 4: You can use the formula and To calculate N'info. TBS can be determined by the value of N'info and the following [pseudo code 1]. The following C corresponds to the number of code blocks included in one TB.

[0249] [Begin pseudocode 1]

[0250]

[0251] [End pseudocode 1]

[0252] In the NR system, when a CB is input to the LDPC encoder, parity bits can be added and output. In this case, the number of parity bits can vary according to the LDCP base graph. The method for transmitting all parity bits generated by LDPC encoding for a specific input can be called full buffer rate matching (FBRM), and the method for limiting the number of parity bits that can be transmitted can be called limited buffer rate matching (LBRM). When resources are allocated for data transmission, the LDPC encoder output is generated as a circular buffer, and the bits of the generated buffer are repeatedly transmitted as many times as the allocated resources, and in this case, the length of the circular buffer can be called Ncb.

[0253] If the number of all parity bits generated by LDPC coding is N, then in the FBRM method, Ncb = N. In the LBRM method, Ncb is min(N, Nref), and Nref is given by is given, and RLBRM can be determined as 2 / 3. To obtain TBSLBRM, the above method for obtaining TBS is used, but TBSLBRM is calculated by assuming the maximum number of layers and the maximum modulation order supported by the terminal in the cell, assuming that the maximum modulation order Qm is 8 when at least one BWP is configured to use an MCS table supporting 256QAM in the cell and the maximum modulation order is 6 (64QAM) when not configured, assuming the code rate is the maximum code rate 948 / 1024, assuming NRE is 156·nPRB and assuming nPRB is nPRB,LBRM. nPRB,LBRM can be given in Table 16 below.

[0254]

Table 16

[0255] Maximum number of PRBs for all configured BWPs across carriers <![CDATA[n PRB，LBRM ]]> Less than 33 32 33 to 66 66 67 to 107 107 108 to 135 135 136 to 162 162 163 to 217 217 Greater than 217 273

[0256] The maximum data rate supported by the terminal in the NR system can be determined by the following equation 2.

[0257] [Equation 2]

[0258] Data rate (in Mbps) =

[0259]

[0260] In the above equation 2, J is the number of carriers grouped by frequency aggregation, Rmax=948 / 1024, Can refer to the maximum number of layers, refers to the maximum modulation order, f(j) refers to the scaling index, and μ refers to the subcarrier spacing. f(j) can be reported by the terminal as one of 1, 0.8, 0.75 and 0.4, and μ can be given in Table 17 below.

[0261]

Table 17

[0262]

[0263] in addition, is the average OFDM symbol length, can be calculated as and is the maximum number of RBs in BW(j). OH(j) is an overhead value, which can be given as 0.14 in the downlink and 0.18 in the uplink in FR1 (frequency bands below 6 GHz), and can be given as 0.08 in the downlink and 0.10 in the uplink in FR2 (frequency bands above 6 GHz). By equation 2, the maximum data rate in the downlink in a cell with a 100 MHz frequency bandwidth at a 30 kHz subcarrier spacing can be calculated as in the following Table 18.

[0264]

Table 18

[0265]

[0266] On the other hand, the actual data rate that can be measured in the actual data transmission of the terminal can be the amount of data divided by the data transmission time. When one TB is transmitted, this can be the value of the TBS divided by the TTI length, or when two TBs are transmitted, it can be the sum of the TBS divided by the TTI length. As an example, as assumed in Table 15, the maximum actual data rate in the downlink in a cell with a 100 MHz frequency bandwidth at a 30 kHz subcarrier spacing can be determined according to the number of allocated PDSCH symbols, as shown in Table 19 below.

[0267]

Table 19

[0268]

[0269]

[0270] Through Table 18, the maximum data rate supported by the terminal can be identified, and through Table 16, the actual data rate according to the allocated TBS can be identified. In this case, depending on the scheduling information, the actual data rate may be greater than the maximum data rate.

[0271] In a wireless communication system, especially an NR system, the data rate that a terminal can support can be agreed upon between the base station and the terminal. This can be calculated using the maximum frequency band, maximum modulation order, and maximum number of layers supported by the terminal. However, the calculated data rate may be different from the value calculated based on the transport block size (TBS) and the transmission time interval (TTI) length of the transport block (TB) used for actual data transmission.

[0272] Therefore, there may be a case where a terminal is allocated a TBS greater than a value corresponding to a data rate supported by the terminal, and in order to prevent this, there may be a restriction on the TBS that can be scheduled according to the data rate supported by the terminal.

[0273] Since the terminal is usually far away from the base station, the signal transmitted from the terminal is received by the base station after the propagation delay. The propagation delay is the value of the path through which the radio wave is transmitted from the terminal to the base station divided by the speed of light, and can generally be the distance from the terminal to the base station divided by the speed of light. In an embodiment, for a terminal located 100km away from the base station, the signal transmitted from the terminal is received by the base station after about 0.34msec. In turn, the signal transmitted from the base station is also received by the terminal after about 0.34msec. As described above, the time for the signal transmitted from the terminal to arrive at the base station can vary depending on the distance between the terminal and the base station. Therefore, when multiple terminals located at different locations transmit signals at the same time, the arrival time at the base station may all be different. In order to solve this problem and allow the signals transmitted from multiple terminals to arrive at the base station at the same time, the uplink signal transmission time of each terminal can vary according to the location. In 5G, NR and LTE systems, this is called timing advance (TA).

[0274] Figure 8 The processing time of the terminal according to the timing advance when the terminal receives a first signal and transmits a second signal in response to the first signal in a 5G or NR system according to an embodiment of the present disclosure is shown.

[0275] When the base station transmits a first signal (uplink scheduling grant (UL grant) or downlink control signal and data (DL grant and DL data)) to the terminal in time slot n 802, the terminal may receive the first signal in time slot n 804. In this case, the terminal may receive the signal later than the time when the base station transmits the signal by a propagation delay time (Tp) 810. According to an embodiment, when the terminal receives the first signal in time slot n 804, the terminal transmits the corresponding second signal (HARQ-ACK / NACK for uplink data or downlink data) in time slot n+4 806. Even when the terminal transmits a signal to the base station, in order to arrive at the base station at a specific time, the terminal may transmit the second signal at a timing 806, which is earlier than time slot n+4 according to the standard that the terminal receives the signal through timing advance (TA) 812. Therefore, in this embodiment, the time when the terminal can prepare to receive uplink scheduling approval, transmit uplink data or receive downlink data, and transmit HARQ ACK or NACK may be a time corresponding to 3 time slots minus TA (814).

[0276] In order to determine the above timing, the base station may calculate the absolute value of the TA of the corresponding terminal. When the terminal initially accesses the base station, the base station may calculate the absolute value of the TA by adding or subtracting the change in the TA value transmitted by the higher layer signaling from the TA value first transmitted to the terminal in the random access step. In the present disclosure, the absolute value of the TA may be a value obtained by subtracting the start time of the nth TTI received by the terminal from the start time of the nth TTI transmitted by the terminal.

[0277] On the other hand, one of the important criteria for the performance of a cellular wireless communication system is packet data latency. For this purpose, in an LTE system, signals are transmitted and received in units of subframes, where the transmission time interval (hereinafter referred to as TTI) is 1 ms. In an LTE system operating as described above, terminals (short TTI UEs) with a transmission time interval shorter than 1 ms can be supported. On the other hand, in a 5G or NR system, the transmission time interval can be shorter than 1 ms. Short TTI terminals are suitable for services where latency is important, such as LTE voice (VoLTE) services and remote control. In addition, short TTI terminals are devices for implementing mission-critical cellular-based Internet of Things (IoT).

[0278] In a 5G or NR system, when a base station transmits a PDSCH including downlink data, the DCI that schedules the PDSCH indicates a K1 value, which is a value corresponding to the timing information of the HARQ-ACK information of the terminal transmitting the PDSCH. When it is not indicated to be transmitted before symbol L1 (including timing advance), the HARQ-ACK information may be transmitted by the terminal to the base station. That is, the HARQ-ACK information may be transmitted from the terminal to the base station at a time equal to or later than symbol L1 (including timing advance). When the HARQ-ACK information is indicated to be transmitted before symbol L1 (including timing advance), the HARQ-ACK information may not be valid HARQ-ACK information in the HARQ-ACK transmission from the terminal to the base station.

[0279] The symbol L1 may be the first symbol in which a cyclic prefix (CP) starts after Tproc,1 from the last time point of the PDSCH. Tproc,1 may be calculated as in Equation 3 below.

[0280] [Equation 3]

[0281] T proc，1＝ (N 1 +d 1，1 )(2048+144)k2 -u ·T c .

[0282] In the above equation 3, N1, d1,1, d1,2, k, μ and TC can be defined as follows.

[0283] - When HARQ-ACK information is transmitted through the uplink control channel (PUCCH), d1,1=0, and when HARQ information is transmitted through the uplink shared channel, data channel (PUSCH), d1,1=1.

[0284] - When the terminal receives multiple activated configured carriers or carriers, the maximum timing difference between the carriers can be reflected in the second signal transmission.

[0285] - In case of PDSCH mapping type A, ie, when the first DMRS symbol position is the 3rd or 4th symbol of the slot, if the position index i of the last symbol of PDSCH is less than 7, then d1,2=7-i is defined.

[0286] -In the case of PDSCH mapping type B, i.e., when the first DMRS symbol position is the first symbol of PDSCH, if the length of PDSCH is 4 symbols, d1,2=3, and if the length of PDSCH is 2 symbols, d1,2=3+d, and d is the number of symbols overlapped between PDSCH and PDCCH, including the control signal used to schedule PDSCH.

[0287] - N1 is defined according to μ, as shown in Table 20 below. μ = 0, 1, 2 and 3 refer to subcarrier spacings of 15 kHz, 30 kHz, 60 kHz and 120 kHz, respectively.

[0288]

Table 20

[0289]

[0290] - N provided in Table 20 above 1 The value can be different, depending on the UE capabilities. c , Δf max 、N f , k, T s , Δf ref and N f,ref They are defined as follows.

[0291] T c =1 / (Δf Max ·N f ), Δf max =480·10 3 Hz,N f =4096, k=T s / T c =64,T s =1 / (Δf Max ·N f，ref ), Δfref =15·10 3 , N f，ref =2048.

[0292] In addition, in the 5G or NR system, when the base station transmits control information including uplink scheduling approval, the terminal can indicate a K2 value corresponding to timing information for transmitting uplink data or PUSCH.

[0293] When PUSCH is not instructed to be transmitted before symbol L2 (including timing advance), the terminal can transmit PUSCH to the base station. That is, PUSCH information can be transmitted from the terminal to the base station at a time equal to or later than symbol L2 (including timing advance). When PUSCH is instructed to be transmitted before symbol L2 (including timing advance), the terminal can ignore the uplink scheduling authorization control information from the base station.

[0294] Symbol L2 may be the first symbol in which the CP of a PUSCH symbol that may be transmitted after Tproc,2 from the last point of the PDCCH including the scheduling grant begins. Tproc,2 may be calculated as in Equation 4 below.

[0295] [Equation 4]

[0296] T proc，2 =max((N 2 +d 2，1 )(2048+144)·k2 -u ·T c , d 2，2 )

[0297] In the above equation 4, N2, d2,1, k, μ and TC can be defined as follows.

[0298] - When the first symbol among the symbols allocated by the PUSCH includes only the DMRS, d2,1=0, otherwise, d2,1=1.

[0299] - When the terminal is configured with multiple activated configured carriers or carriers, the maximum timing difference between the carriers may be reflected in the second signal transmission.

[0300] - N2 is defined according to μ, as shown in Table 21 below. μ = 0, 1, 2 and 3 refer to subcarrier spacings of 15 kHz, 30 kHz, 60 kHz and 120 kHz, respectively.

[0301]

Table 21

[0302] μ <![CDATA[PUSCH Preparation Time N 2 [Symbol]]]> 0 10 1 12 2 23 3 36

[0303] - The N2 value provided in Table 21 above may be different values, depending on the UE capability. Tc, Δfmax, Nf,k, Ts, Δfref and Nf,ref are defined as follows respectively.

[0304] T c =1 / (Δf Max ·N f ), Δf max =480·10 3 Hz,N f =4096, k=T s / T c =64, T s =1 / (Δf Max ·N f，ref ), Δf ref =15·10 3 , N f，ref =2048.

[0305] On the other hand, a 5G or NR system can configure a band part (BWP) within one carrier and specify a specific terminal to transmit and receive within the configured BWP. This may be intended to reduce the power consumption of the terminal. The base station can configure multiple BWPs and change the activated BWP in the control information. The time that the terminal can use when the BWP changes can be defined as shown in Table 22 below.

[0306]

Table 22

[0307]

[0308]

[0309] In Table 22, frequency range FR1 may refer to a frequency band below 6 GHz, and frequency range FR2 may refer to a frequency band above 6 GHz, and may be classified as shown in Table 22 above. Typically, FR2 may refer to a high frequency band close to the mmWave frequency band, and FR1 may refer to a relatively low frequency band compared to FR2. In the above embodiment, type 1 and type 2 may be determined according to UE capabilities. In the above embodiment, scenarios 1, 2, 3, and 4 are given in Table 23 below.

[0310]

Table 23

[0311] Center frequency change The center frequency remains unchanged Frequency bandwidth change Scene 3 Scenario 2 Frequency bandwidth remains unchanged Scenario 1 Scenario 4, if the subcarrier spacing changes

[0312] Fig. 9 An example of scheduling and transmitting data (e.g., TB) according to a time slot, receiving HARQ-ACK feedback for the data, and performing retransmission according to the feedback is shown. Fig. 9, TB1 900 is initially transmitted in time slot 0 902, and corresponding ACK / NACK feedback 904 is transmitted in time slot 4 906. If the initial transmission of TB1 fails and a NACK is received, a retransmission 910 of TB1 may be performed in time slot 8 908. The timing of transmitting ACK / NACK feedback and the timing of performing retransmissions may be predetermined or may be determined based on control information and / or values ​​indicated by higher layer signaling.

[0313] Fig. 9 An example of scheduled transmission from TB1 to TB8 in order according to the time slots is shown starting from time slot 0. For example, this can be transmitted by assigning HARQ process IDs 0 to 7 to TB1 to TB8, respectively. If the number of HARQ process IDs that the base station and the terminal can use is only 4, it may not be possible to transmit continuously for 8 different TBs.

[0314] Fig.10 An example of a communication system using a satellite according to an embodiment of the present disclosure is shown. For example, when the terminal 1001 transmits a signal to the satellite 1003 through a service link, the satellite 1003 transmits a signal to the base station 1005 through a feeder link, and the base station 1005 processes the received signal and transmits a signal including a request for a subsequent operation to the terminal 1001, which can be transmitted again through the satellite 1003. Since the distance between the terminal 1001 and the satellite 1003 is long and the distance between the satellite 1003 and the base station 1005 is also long, the time required to transmit and receive data from the terminal 1001 to the base station 1005 becomes longer.

[0315] Fig.11 The earth orbit period of the communication satellite according to the embodiment of the present disclosure according to the altitude and height of the satellite is shown. The satellite used for communication can be classified into a low earth orbit (LEO), a medium earth orbit (MEO) and a geostationary earth orbit (GEO) according to the orbit of the satellite. Generally, GEO 1100 refers to a satellite with an altitude of about 36,000km, MEO 1110 refers to a satellite with an altitude of 5,000km to 15,000km, and LEO can refer to a satellite with an altitude of 500km to 1,000km. Of course, it is not limited to the above examples.

[0316] According to an embodiment of the present disclosure, the orbital period of the Earth varies according to each altitude, and is about 24 hours for GEO 1100, about 6 hours for MEO 1110, and about 90 minutes to 120 minutes for LEO 1130. Low Earth orbit (~2,000 km) satellites may have an advantage over geostationary orbit (36,000 km) satellites in terms of propagation delay (which can be understood as the time required for a signal transmitted by a transmitter to reach a receiver) and loss due to their relatively low altitude.

[0317] Fig.12 Satellite-to-terminal direct communication according to an embodiment of the present disclosure is shown. A satellite 1200 positioned by a rocket at an altitude of 100 km or more transmits and receives signals with a terminal 1210 on the ground, and also transmits and receives information with a ground station 1220 connected to a DU cluster 1230 on the ground.

[0318] Fig.13 A usage scenario of satellite-to-terminal direct communication according to an embodiment of the present disclosure is shown.

[0319] Satellite-to-device direct communication can support specialized communication services in the form of supplementing the coverage limitations of the ground network. As an example, by implementing the satellite-to-device direct communication function in the user terminal, emergency rescue and / or disaster signals can be transmitted and received for users in places other than the ground network communication coverage (1300), mobile communication services can be provided for users in areas such as ships and / or aviation where ground network communication is not possible (1310), the location of ships, trucks and / or drones can be tracked and controlled in real time without boundary restrictions (1320), and satellite communication can also be used as a backhaul for the base station and the backhaul function can be performed by supporting the satellite communication function in the base station when the physical distance is far (1330).

[0320] Fig.14 An example of calculating an expected data throughput in an uplink when a LEO satellite at an altitude of 1200 km and a terminal on the ground perform direct communication according to an embodiment of the present disclosure is shown.

[0321] In the uplink, when the effective isotropic radiated power (EIRP) of the ground terminal's transmission power is 23dBm, the path loss of the wireless channel to the satellite is 169.8dB, and the satellite receiving antenna gain is 30dBi, the achievable signal-to-noise ratio (SNR) is estimated to be -2.63dB. In this case, the path loss may include path loss in the external space, loss in the atmosphere, etc. Assuming that the signal-to-interference ratio (SIR) is 2dB, the signal-to-interference-to-noise ratio (SINR) is calculated to be -3.92dB, and in this case, when using a 30kHz subcarrier spacing and a 1PRB frequency resource, a transmission rate of 112kbps can be achieved.

[0322] Fig.15 An example of calculating an expected data throughput in an uplink when a GEO satellite at an altitude of 35,786 km and a terminal on the ground perform direct communication according to an embodiment of the present disclosure is shown.

[0323] In the uplink, when the transmission power EIRP of the ground terminal is 23dBm, the path loss of the wireless channel to the satellite is 195.9dB, and the satellite receiving antenna gain is 51dBi, the achievable SNR is estimated to be -10.8dB. In this case, the path loss may include the path loss in the external space, the loss in the atmosphere, etc. Assuming that the SIR is 2dB, the SINR is calculated to be -11dB, and in this case, when using a 30kHz subcarrier spacing and a frequency resource of 1PRB, a transmission rate of 21kbps can be achieved, which may be the result of performing three repeated transmissions.

[0324] Fig.16 The path loss value between a terminal and a satellite according to a path loss model and the path loss between a terminal and a ground network communication base station according to a path loss model according to an embodiment of the present disclosure are shown.

[0325] exist Fig.16 In which d corresponds to the distance, and fc is the frequency of the signal. In free space where the terminal communicates with the satellite, the path loss (FSPL, 1600) is inversely proportional to the square of the distance, but the path loss on the ground where there is air when communicating between the terminal and the ground gNB (PL2, PL'Uma-NLOS, 1610, 1620) may be inversely proportional to approximately the fourth power of the distance. d3D refers to the straight-line distance between the terminal and the base station, hBS is the height of the base station, and hUT is the height of the terminal. d'BP = 4x hBS x hUT x fc / c. fc is the center frequency in Hz, and c is the speed of light in m / s.

[0326] In satellite communications (or non-terrestrial networks, NTNs), Doppler shift, ie, a frequency shift (offset) of the transmitted signal, occurs when a satellite moves continuously and rapidly.

[0327] Fig.17 The altitude and position of a satellite according to an embodiment of the present disclosure, as well as a formula and results for calculating the amount of Doppler frequency shift experienced by a signal transmitted from a satellite according to the position of a ground user when the signal is received by the ground user.

[0328] The radius of the Earth is R, h is the altitude of the satellite, v is the speed of the satellite orbiting the Earth, and fc is the frequency of the signal. The speed of the satellite can be calculated from the altitude of the satellite, which is the speed at which the gravity, which is the force of the Earth pulling on the satellite, and the centripetal force generated by the satellite's orbit are equal, and this can be calculated as Fig.18 Calculate as shown.

[0329] Fig.18 The velocity of a satellite calculated from the altitude of the satellite according to an embodiment of the present disclosure is shown.

[0330] like Fig.17 As indicated, the angle α is determined by the elevation angle 0, and thus the value of the Doppler shift is determined according to the elevation angle 0.

[0331] Fig.19 The Doppler shift experienced by different terminals within one beam transmitted by a satellite to the ground according to an embodiment of the present disclosure is shown.

[0332] exist Fig.19 In FIG. 1 , the Doppler shift experienced by terminal 1 1900 and terminal 2 1910 according to the elevation angle θ is calculated. This is the result of assuming that the center frequency is 2 GHz, the satellite altitude is 700 km, the beam diameter from the ground is 50 km, and the terminal speed is 0. In addition, the Doppler shift calculated in the present disclosure ignores the effect of the earth's rotation speed, and this is because the earth's rotation speed is slower than the satellite speed, so the effect is considered to be small.

[0333] Fig. 20 The difference in Doppler shift occurring within one beam depending on the position of a satellite determined from an elevation angle according to an embodiment of the present disclosure is shown.

[0334] It can be seen that when the satellite is positioned directly above the beam (that is, when the elevation angle is 90 degrees), the Doppler shift within the beam (or cell) is the largest. This may be because when the satellite is located above the center, the Doppler shift values ​​at one end and the other end of the beam have positive and negative values, respectively.

[0335] On the other hand, in satellite communications, since the satellite is far away from users on the ground, a large delay time occurs compared to terrestrial network communications.

[0336] Fig.21 The delay time from the terminal to the satellite and the round-trip delay time between the terminal-satellite-base station depending on the position of the satellite determined based on the elevation angle according to an embodiment of the present disclosure are shown.

[0337] The first graph 2100 shows the delay time from the terminal to the satellite, and the second graph 2110 shows the round trip delay time between the terminal-satellite-base station. In this case, it is assumed that the delay time between the satellite and the base station is the same as the delay time between the terminal and the satellite.

[0338] Fig. 22 The maximum difference in round-trip delay time according to the user position within one beam according to an embodiment of the present disclosure is shown.

[0339] For example, when the beam radius (or cell radius) is 20 km, the difference in round-trip delay time to the satellite experienced differently by terminals at different positions within the beam depending on the position of the satellite can be considered to be about 0.28 ms or less.

[0340] In satellite communication, when a terminal transmits a signal to and receives a signal from a base station, the signal may be transmitted through a satellite. That is, in a downlink, a satellite receives a signal transmitted from a base station to a satellite and then delivers the signal to a terminal, and in an uplink, a satellite receives a signal transmitted from a terminal and then delivers the signal to a base station. After receiving the signal, the satellite may perform only a frequency shift and then transmit the signal, or may perform signal processing such as decoding and re-encoding based on the received signal and transmit the signal.

[0341] In the case of LTE or NR, the terminal can access the base station through the following process.

[0342] -Step 1: The terminal receives a synchronization signal (or a synchronization signal block (SSB) which may include a broadcast signal) from a base station. The synchronization signal may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The synchronization signal may include information such as a time slot boundary, a frame number, a downlink configuration, and an uplink configuration of a signal transmitted from a base station. In addition, through the synchronization signal, the terminal may obtain a subcarrier offset, scheduling information for system information transmission, and the like.

[0343] - Step 2: The terminal receives system information (System Information Block: SIB) from the base station. The SIB may include information for initial access and random access. The information for performing random access may include resource information for transmitting a random access preamble.

[0344] -Step 3: A random access preamble (or message 1, msg1) is transmitted to the random access resource configured in step 2. The preamble may be a signal determined by using a predetermined sequence based on the information configured in step 2. The base station receives the preamble transmitted from the terminal. The base station attempts to receive the preamble configured according to the resource configured by the base station without knowing which terminal transmits the preamble, and if the reception is successful, the base station can know that at least one terminal transmits the preamble.

[0345] -Step 4: When the preamble is received in step 3, the base station transmits a random access response (RAR, or message 2, msg2) in response. In this step, the terminal that transmits the random access preamble in step 3 may attempt to receive the RAR transmitted from the base station. The RAR is transmitted on the PDSCH, and the PDCCH that schedules the PDSCH is transmitted together or in advance. A CRC scrambled with the RA-RNTI value is added to the DCI for scheduling the RAR, and the DCI (and CRC) is channel-coded and then mapped to the PDCCH and transmitted. The RA-RNTI may be determined based on the time and frequency resources where the preamble in step 3 is transmitted.

[0346] The maximum time limit for the terminal transmitting the random access preamble in step 3 to receive the RAR may be configured in the SIB transmitted in step 2. The maximum time limit may be configured to be limited, for example, to a maximum of 10ms or 40ms. That is, if the terminal transmitting the preamble in step 3 does not receive the RAR within a time determined based on the configured maximum time of, for example, 10ms, the terminal may transmit the preamble again. The RAR may include scheduling information that allocates resources for the signal transmitted from the terminal in the next step (step 5).

[0347] Fig.23 An example of the information structure of RAR (MAC payload) according to an embodiment of the present disclosure is shown.

[0348] This may be the MAC payload format (fallback RAR) of Msg B. RAR 2300 may be, for example, a MAC PDU and may also include information 2310 about the timing advance (TA) to be applied by the terminal (e.g., a timing advance command field) and a temporary C-RNTI value 2320 to be used from the next step.

[0349] *R field: For example, a reserved bit can be configured as "0".

[0350] * Timing Advance Command field 2310: The Timing Advance Command field indicates an index value TA for controlling the timing adjustment amount that the MAC entity can apply. The size of the Timing Advance Command field is, for example, 12 bits.

[0351] *UL Grant field: The UL Grant field indicates resources to be used in uplink, and the size of the UL Grant field is, for example, 27 bits.

[0352] * Temporary C-RNTI field 2320: The Temporary C-RNTI field indicates a temporary identifier used by the MAC entity during random access, and the size of the Temporary C-RNTI field may be 16 bits.

[0353] - Step 5: The terminal receiving the RAR in step 4 transmits message 3 (msg3) to the base station according to the scheduling information included in the RAR. The terminal may transmit msg3 including its own unique ID value. The base station may attempt to receive msg3 according to the scheduling information transmitted by the base station in step 4.

[0354] -Step 6: The base station receives msg3, identifies the ID information of the terminal, generates message 4 (msg4) including the ID information of the terminal, and transmits message 4 to the terminal. The terminal that transmits msg3 in step 5 may then attempt to receive msg4 transmitted in step 6. After decoding, the terminal that has received Msg4 may compare the ID value included in msg4 with the ID value transmitted by the terminal in step 5 to identify whether msg3 transmitted by the terminal has been received by the base station. There may be a limit on the time after the terminal transmits msg3 in step 5 until the terminal receives msg4 in step 6, and the maximum time may also be configured from the SIB in step 2.

[0355] When the initial access procedure using the above steps is applied to satellite communication, the propagation delay time required for satellite communication may be a problem. For example, in step 3, the terminal can transmit a random access preamble (or PRACH preamble) and the period (random access window) during which the RAR is received in step 4 (i.e., the maximum time spent on reception) can be configured by ra-ResponseWindow, which can be configured to a maximum of about 10ms in a conventional LTE or 5G NR system.

[0356] Fig.24 An example of the relationship between PRACH preamble configuration resources and RAR reception time in an LTE system according to an embodiment of the present disclosure is shown.

[0357] refer to Fig.24 In the case of LTE, the random access window 2410 starts 3 ms after the random access preamble (PRACH) is transmitted (2400), and when the terminal receives the RAR within the random access window (2420), it can be determined that the transmission of the PRACH preamble is successful.

[0358] Fig.25An example of the relationship between PRACH preamble configuration resources and RAR reception time in a 5G NR system according to an embodiment of the present disclosure is shown.

[0359] refer to Fig.25 In the case of NR, the random access window 2510 starts from the control information region for RAR scheduling that first appears after the random access preamble (PRACH) 2500 is transmitted. When the terminal receives the RAR within the random access window 2520, it can be determined that the transmission of the PRACH preamble is successful.

[0360] As an example, TA for uplink transmission timing in a 5G NR system can be determined as follows. First, T c =1 / (Δf max ·N f ), where Δf max =480·103Hz and N f =4096. In addition, correspondingly, k=T s / T c =64,T s =1 / (Δf ref ·N f,ref ), Δf ref =15·103Hz and N f,ref =2048.

[0361] Fig.26 An example of timing of downlink frames and uplink frames of a terminal according to an embodiment of the present disclosure is shown.

[0362] The terminal can advance the uplink frame by T based on the downlink frame timing. TA =(N TA +N TA,offset )TC to perform uplink transmission. In the above, N TA The value of may be transmitted through RAR or may be determined based on MAC CE, and N TA,offset It may be determined according to terminal configuration or based on a predetermined value.

[0363] The RAR of the 5G NR system can indicate a TA value, and in this case, TA can indicate one of 0, 1, 2, ..., 3846. In this case, if the subcarrier spacing (SCS) of the RAR is 2 μ 15kHz, then N TA Can be determined as N TA =T A ·16·64 / 2 μAfter the terminal completes the random access process, the changed value of TA may be indicated from the base station, and this may be indicated by MAC CE, etc. The TA information indicated by MAC CE may indicate a value among 0, 1, 2, ..., 63, which is added to or subtracted from the existing TA value and used to calculate the new TA value, and thus, the TA value may be newly calculated as N TA_new =T A_old +(T A -31)·16·64 / 2 μ The TA value indicated in this manner may be applied by the terminal for uplink transmission after a predetermined period of time.

[0364] Fig. 27 An example of continuous movement of a satellite in an angle of a terminal located on or on the ground of the earth as the satellite orbits the earth in a satellite orbit according to an embodiment of the present disclosure is shown.

[0365] Since the distance between a terminal and a satellite varies according to the elevation angle at which the terminal looks at the satellite, the propagation delay between the terminal, the satellite, and the base station varies.

[0366] Fig.28 An example of the structure of an artificial satellite according to an embodiment of the present disclosure is shown.

[0367] The satellite may be composed of a solar panel or solar array 2800 for photovoltaic or solar power generation, a transmit / receive antenna (main mission antenna) 2810 for communicating with a terminal, a transmit / receive antenna (feeder link antenna) 2820 for communicating with a ground station, a transmit / receive antenna (inter-satellite link) 2830 for inter-satellite communication, a processor for controlling transmission and reception and performing signal processing, etc. Of course, it is not limited to the above examples, and an artificial satellite may include more than Fig.28 In addition, according to an embodiment of the present disclosure, if the satellite does not support inter-satellite communication, the antenna for transmitting and receiving inter-satellite signals may not be deployed. Fig.28 Although the L band of 1 GHz to 2 GHz is shown to be used for communication with the terminal, high frequency bands such as the K band (18 GHz to 26.5 GHz), the Ka band (26.5 GHz to 40 GHz), and the Ku band (12 GHz to 18 GHz) may also be used.

[0368] In addition, in various embodiments of the present disclosure, the term "base station (BS)" may refer to a transmission point (TP), a transmission reception point (TRP), an enhanced Node B (eNodeB or eNB), a 5G base station (gNB), a macro base station, a femto base station, a WiFi access point (AP), or any component (or collection of components) configured to provide wireless access based on the type of wireless communication system, such as other wireless-enabled devices. The base station may provide one or more wireless protocols, such as wireless access according to 5G 3GPP New Air Interface / Access (NR), Long Term Evolution (LTE), Advanced LTE (LTE-Advanced: LTE-A), High Speed ​​Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc.

[0369] In addition, in various embodiments of the present disclosure, the term "terminal" may refer to any component, such as "user equipment (UE)", "mobile station", "subscriber station", "remote terminal", "wireless terminal", "reception point" or "user device". For convenience, the term "terminal" is used in the present disclosure to refer to a device that accesses a base station, regardless of whether the terminal should be considered as a mobile device (such as a mobile phone or a smart phone) or a fixed device (such as a desktop computer or a vending machine).

[0370] In addition, in various embodiments of the present disclosure, the term "TA" may be used interchangeably with "TA information", "TA value" or "TA index".

[0371] In various embodiments of the present disclosure, data or control information transmitted from a base station to a terminal may be referred to as a first signal, and an uplink signal associated with the first signal may be referred to as a second signal. For example, the first signal may include DCI, UL authorization, PDCCH, PDSCH, RAR, etc., and the second signal associated with the first signal may include PUCCH, PUSCH, msg 3, etc.

[0372] In addition, there may be an association between the first signal and the second signal. As an example, when the first signal is a PDCCH including an UL grant for uplink data scheduling, the second signal corresponding to the first signal may be a PUSCH including uplink data. On the other hand, the gap between the time points of transmitting and receiving the first signal and the second signal may be a value predetermined between the terminal and the base station. Conversely, the gap between the time points of transmitting and receiving the first signal and the second signal may be determined by an indication from the base station or by a value transmitted via high-layer signaling.

[0373] In direct terminal-satellite communication, since the distance between terminal-satellite and satellite-base station is long and the satellite is constantly moving, when the signal transmitted by the base station or terminal is received by the terminal or base station, a time offset occurs due to delay time, etc. Therefore, the present disclosure provides a method and an apparatus, in which the base station indicates time offset information and the terminal corrects the time offset accordingly, so that the time offset can be corrected. The following embodiments are described assuming communication between a terminal, a satellite, and a ground station, but communication between a satellite base station and a terminal is not excluded. In the present disclosure, time offset can be used interchangeably with timing advance. The methods and apparatus provided in various embodiments of the present disclosure can be applied not only to satellite communication systems, but also to ground communication systems. In addition, the following embodiments can be operated in combination with each other.

[0374] In an embodiment of the present disclosure, a method and apparatus are described for a terminal to directly determine (e.g., calculate) a TA value and apply the determined TA value when the terminal transmits an uplink signal to a satellite or a base station. In addition, an embodiment of the present disclosure describes a method and apparatus in which a base station or a satellite indicates a TA value to be applied by the terminal when the terminal transmits an uplink signal to a satellite or a base station, and thus the terminal transmits the uplink signal by applying the indicated TA value. In addition, an embodiment of the present disclosure describes a method and apparatus for adaptively determining a TA value to be applied when a terminal transmits an uplink signal to a satellite or a base station. More specifically, an embodiment of the present disclosure describes a method and apparatus in which the terminal determines the TA value by itself, and as described in the present disclosure, the base station or the satellite indicates the TA value to the terminal and the terminal determines the TA value by adaptively selecting one of the methods for applying the indicated TA value.

[0375] First, the terminal may compare the uplink transmission time with the downlink reception time to achieve uplink synchronization, and advance the uplink transmission time by TTA compared to the downlink reception time based on the comparison result. TTA calculated for the TA of satellite communication may be expressed as Equation 5 below.

[0376] [Equation 5]

[0377] T TA =(N TA +N TA,UE-specific +N TA,common +N TA,offset )XT c

[0378] In Equation 5, T c can be given as T c =1 / (Δf max ·N f ), and Δf max =480·103Hz and Nf =4096. In equation 5, N TA It may be a value determined based on the TA value included in the RAR or MAC CE received from the base station, and N TA,offset It can be a value fixed or promised in advance. In equation 5, N TA,UE-specific is the TA correction value measured by the terminal based on the position of the terminal itself and the satellite (or reference position), N TA,common It may be a TA correction value configured or indicated by the base station by using a higher layer signaling or a physical layer signal.

[0379] Compared with the following equation 6 as a conventional TA application method, equation 5 may be one in which the parameter N is added. TA,UE-specific and N TA,common formula.

[0380] [Equation 6]

[0381] T TA =(N TA +N TA,offset )XT c

[0382] Fig.29 The terminal according to an embodiment of the present disclosure determines N from the initial access TA An example of the process.

[0383] refer to Fig.29 , the terminal is N TA = 0 transmits a PRACH preamble code to the base station, and the base station transmits an indication N to the terminal TA Thereafter, the terminal applies N TA =A to transmit PUSCH, and the base station transmits an indication ΔN to the terminal TA After that, the terminal can apply N TA =A+ΔN TA To transmit PUSCH.

[0384] Fig.30 The terminal according to an embodiment of the present disclosure determines N from the initial access TA 、N TAUE-specific and N TA,common An example of the process.

[0385] refer to Fig.30 The base station transmits satellite information, N TA,common and drift rate configuration information. Thereafter, the terminal assumes that N TA = 0, and by applying N measured by the terminal TA,UE-specific and the configured N TA,commonTo transmit the PRACH preamble code to the base station. Thereafter, the base station transmits an indication N to the terminal. TA RAR, and can update N TA,UE-specific and N TA,common . Thereafter, the terminal assumes that N TA =A, and according to T calculated based on Equation 5 TA To transmit PUSCH, and the base station can transmit an indication ΔN to the terminal TA MAC CE. After that, N TA,UE-specific and N TA,common , and the terminal can apply N TA =A+ΔN TA And the application of updated N TA,UE-specific and N TA,common According to T calculated based on Equation 5 TA Transmit PUSCH.

[0386] Based on TA=0, 1, 2, ..., 3846 transmitted in RAR or msg B, T TA Can be determined as N TA =TA·16·64 / 2 μ In addition, TA=0, 1, 2, ..., 63 is transmitted to the MAC CE and can be updated to N TA_new =TA_old+(TA-31)·16·64 / 2 μ In addition, Δf max ·N f , a TA value transmitted from RAR or msg B, or a TA value transmitted from MAC CE, etc. may be changed according to the communication system. In addition, when the terminal performs operations such as N based on the TA transmitted from MAC CE TA_new =T A_old +(T A -M)·16·64 / 2 μ When the TA is updated, if the maximum value of the TA is greater than 63, the M value may be greater than or equal to 31, and if the maximum value of the TA is less than 63, the terminal may determine N based on the M value less than or equal to 31. TA_new , that is, the updated N TA value.

[0387] Fig.31 Another example of an operation process of a terminal in a communication system according to an embodiment of the present disclosure is shown.

[0388] The terminal can be based on Fig.31 The initial access procedure is performed according to the procedure described in , and the TA is determined after performing the initial access procedure, and this is explained in detail as follows.

[0389] First, in operation 3111, the terminal may detect a synchronization signal and a PBCH block (SSB) received from a base station. In operation 3113, the terminal may decode a system information block (SIB) based on the detected SSB. The terminal may detect information about a random access channel (RACH) resource by decoding the SIB.

[0390] In operation 3115, the terminal may obtain (or decode) satellite information by decoding the SIB. According to an embodiment of the present disclosure, the satellite information may include at least one of various parameters such as satellite position information. In operation 3115, the terminal may obtain a UE-specific TA correction value based on the obtained satellite information and the positions (or reference positions) of the terminal and the satellite, for example, N TA,UE-specific In operation 3117, the terminal may obtain (or decode) the common TA offset by decoding the SIB, for example, N TA,common .

[0391] In operation 3119, the terminal may TA,UE-specific and N TA,common The terminal may calculate the TA and transmit the PRACH to the base station by applying the calculated TA. In operation 3121, the terminal may receive the RAR including the TA value in response to the PRACH transmission. In operation 3123, the terminal may adjust the TA based on the received RAR.

[0392] In operation 3125, the terminal may transmit msg3 to the base station by applying TA. msg3 is part of the random access procedure and may indicate a message transmitted on an uplink shared channel (UL-SCH) including a C-RNTI MAC CE or a common control channel (CCCH) SDU, and may be the first scheduled transmission of the random access procedure. In operation 3127, the terminal may receive a MAC CE including a TA adjustment value from the base station. In operation 3129, the terminal may transmit PUSCH or / and PUCCH by applying TA based on the TA adjustment value included in the MAC CE.

[0393] Compared with the operation process of the terminal in other embodiments of the present disclosure, Fig.31 The operation process of the terminal described in (i.e., the process of performing the initial access process and determining the TA after performing the initial access process) can be summarized as shown in Table 24 below.

[0394]

Table 24

[0395]

[0396]

[0397] In addition, Fig.31 During the operation of the terminal described in the embodiment, the order of some operations may be changed, and as an example, the order of decoding satellite information and decoding common TA offset may be changed.

[0398] On the other hand, reference Fig.31 The operation process of the terminal in the communication system according to various embodiments of the present disclosure is shown, but of course, the operation process of the terminal in the communication system according to various embodiments of the present disclosure can be Fig.31 As an example, although Fig.31 The sequential steps are shown in Fig.31 The steps described in may overlap, may occur in parallel, may occur in a different order, or one or more steps may occur multiple times.

[0399] Fig.32 Another example of an operation process of a terminal in a communication system according to an embodiment of the present disclosure is shown.

[0400] The terminal can be based on Fig.32 The initial access procedure is performed according to the procedure described in , and the TA is determined after performing the initial access procedure, and this is explained in detail as follows. In particular, Fig.31 An operation process of a terminal based on a random access process for a 4-step random access (RA) type is shown, and Fig.32 The operation procedure of the terminal shown in may be a terminal operation procedure based on a random access procedure for a 2-step RA type.

[0401] First, in operation 3211, the terminal detects the SSB received from the base station. In operation 3213, the terminal decodes the SIB based on the detected SSB. The terminal can obtain information about RACH resources by decoding the SIB.

[0402] In operation 3215, the terminal may obtain (or decode) satellite information by decoding the SIB. According to an embodiment of the present disclosure, the satellite information may include at least one of various parameters such as satellite position information. In operation 3215, the terminal may obtain a UE-specific TA correction value based on the decoded satellite information and the positions (or reference positions) of the terminal and the satellite, for example, N TA,UE-specific In operation 3217, the terminal may obtain (or decode) the common TA offset by decoding the SIB, for example, N TA,common In operation 3219, the terminal TA,UE-specific and N TA,commonto calculate the TA, and transmit msgA to the base station by applying the calculated TA. According to one embodiment of the present disclosure, msgA may be a preamble and payload transmission for a random access procedure of a 2-step random access (RA) type. In operation 3221, the terminal may receive msgB including a TA value from the base station. According to an embodiment of the present disclosure, msgB is a response to msgA in a random access procedure of a two-step RA type, and may include a response to contention resolution, a backoff indication, and a backoff indication. In operation 3223, the terminal may adjust the TA based on the TA adjustment value included in msgB. In operation 3225, the terminal may transmit PUSCH and / or PUCCH by applying the adjusted TA.

[0403] Compared with the operation process of the terminal in other embodiments of the present disclosure, Fig.32 The operation process of the terminal described in (i.e., the process of performing the initial access process and determining the TA after performing the initial access process) can be summarized as shown in Table 25 below.

[0404]

Table 25

[0405]

[0406] In addition, Fig.32 During the operation of the terminal described in the embodiment, the order of some operations may be changed, and as an example, the order of decoding satellite information and decoding common TA offset may be changed.

[0407] On the other hand, reference Fig.32 The operation process of the terminal in the communication system according to various embodiments of the present disclosure is shown, but of course, the operation process of the terminal in the communication system according to various embodiments of the present disclosure can be Fig.32 As an example, although Fig.32 The sequential steps are shown in Fig.32 The steps described in may overlap, may occur in parallel, may occur in a different order, or one or more steps may occur multiple times.

[0408] On the other hand, N used in the embodiments of the present disclosure TA,UE-specific is a value calculated and applied by the terminal. Therefore, the base station may not know N calculated by the terminal. TA,UE-specific In addition, the N calculated by the terminal TA,UE-specific The value may change over time due to satellite or terminal movement.

[0409] Therefore, in embodiments of the present disclosure, the base station may need to take into account N which may change over time. TA,UE-specific value to control the TA of the terminal, and therefore the terminal may need to be configured to update N TA,UE-specific Therefore, the terminal can update N based on the following method:TA,UE-specific A value, for example, any one of methods 1-1 to 1-6, or a method combining at least two of methods 1-1 to 1-6.

[0410] -Method 1-1: The terminal always updates N upon receiving a SIB including satellite information (eg, including satellite information, etc.) TA,UE-specific When the terminal determines that the SIB is received from the base station or when a paging signal indicating SIB update is received from the base station, method 1-1 may be applied.

[0411] -Method 1-2: The base station can indicate the change rate of TA separately, for example, N TA,UE-specific , and may also configure a period and an offset for recalculating the TA value (e.g., for updating the TA value) according to the rate of change of the TA. In this case, the terminal updates the TA at a time determined according to the update period and the offset, e.g., N TA,UE-specific , and the amount of TA updated by the terminal can be determined according to the change rate of TA. In various embodiments of the present disclosure, the base station can indicate the change rate of TA based on an explicit method or an implicit method.

[0412] -Method 1-3: The base station can configure the terminal to update N based on the location of the satellite and the terminal TA,UE-specific In this case, the terminal may update the TA at a relevant time determined according to the update period and offset configured by the base station. In various embodiments of the present disclosure, the base station may indicate the update period and offset based on an explicit method or an implicit method.

[0413] - Method 1-4: In at least some cases of performing uplink transmission (e.g., PUCCH / PUSCH, PRACH, SRS transmission, etc.), the terminal may always update and apply N at relevant times (e.g., at relevant time slots). TA,UE-specific (It can be executed every time, in regular cycles, or at irregular times).

[0414] -Method 1-5: The terminal updates N based on the expiration time of the TA command transmitted by the base station through the MAC CE TA,UE-specific As an example, when TA expires, the terminal updates N TA,UE-specific . The expiration of the TA command may be based on a timer for the TA command, indicating that the timer value has reached a specific time point. The timer for the TA command may be configured as a timeAlignmentTimer, which may be a parameter for how long the uplink time synchronization is correct. After receiving a new TA command, the terminal may start or restart the timeAlignmentTimer. When the timeAlignmentTimer expires, the terminal may clear the HARQ buffer and reconfigure the RRC configuration, etc.

[0415] -Method 1-6: Introducing N TA,UE-specific The terminal can update NTA,UE-specific based on the new timer timeAlignmentTimer_UEspecific. TA,UE-specific Or transmit to the base station about N TA,UE-specific When the timeAlignmentTimer_UEspecific expires, the terminal can recalculate and update N TA,UE-specific , N TA,UE-specific Configured to 0 or perform PRACH transmission.

[0416] The embodiment provides a method and apparatus for transmitting (reporting) a timing advance (TA) value that a terminal is applying or has applied to a base station or a satellite. In the present disclosure, a satellite may be an object located high above the ground, and may be a concept including an airplane, an airship, etc.

[0417] The terminal may perform an operation of transmitting the TA value being applied by the terminal to the base station. This may be to notify the base station of the applied TA value when the terminal applies the TA value without a separate instruction from the base station, or to identify or determine how the terminal applies the TA value indicated by the base station. For example, the operation may be performed so that when the satellite to which the terminal is connected changes, the satellite newly connected to the terminal can identify the TA value of the terminal. As an example, the terminal may independently apply a TA calculated based on the position of the terminal and the satellite.

[0418] The terminal may report the TA value to the base station using one or a combination of at least two of the following methods.

[0419] -Method 2-1: The base station may trigger the TA value report of the terminal through DCI. The base station may trigger the TA value report through some bit field values ​​or a combination of bit field values ​​of the DCI. The field indicating the triggering of the TA value report is included in the DCI, and in this case, when the field of the received DCI is configured as a specific value, the terminal may understand that the TA value report has been triggered. Alternatively, when the value of one or more fields (for example, for other purposes) included in the DCI is configured as a predetermined value, the terminal may understand that the TA value report has been triggered. The terminal may transmit the TA value to the base station at a specific time point based on the time point when the DCI is received.

[0420] -Method 2-2: The base station can trigger the TA value report of the terminal through MAC CE. The base station can trigger the TA value report by using some bit values ​​or bit field values ​​of MAC CE, and the terminal can transmit the TA value to the base station when receiving the MAC CE or at a predetermined time after receiving the MAC CE.

[0421] -Method 2-3: The base station may indicate which TA value the terminal may report through RRC configuration. As an example, the base station may determine at what point in time the terminal may report the TA value by configuring a period and offset value for TA reporting and / or a specific condition for the terminal to report the TA value through high-level signaling, and in this case, the reference TA value application time (i.e., the time when the TA value to be reported is applied, which may be referred to as a TA value reference point) may also be specified. The specific condition for the terminal to report the TA value may be, for example, a case where the TA value is greater than or equal to a predetermined value, or a case where the distance between the terminal and the satellite is greater than or equal to a preset value, and the preset value may be configured through high-level signaling, information transmitted from the SIB, etc., or may be a fixed value.

[0422] -Method 2-4: The terminal may report the TA value without a separate trigger from the base station. For example, method 4 may be that the terminal transmits information indicating the TA value to the base station according to a specific condition, and the specific condition may be predetermined, such as a condition of the time of performing TA value reporting or a condition of a comparison result between the TA value applied by the terminal and a specific threshold, etc. (without signaling for triggering such as DCI, MAC CE, RRC, etc. from the base station).

[0423] According to an embodiment of the present disclosure, when transmitting a TA value, the terminal may transmit the TA value by using a physical channel such as PUCCH, PUSCH, etc., or may transmit the TA value information to the base station through high-layer signaling. When the terminal transmits the TA value information by using a physical channel, resources to be used for reporting the TA value information may be configured through high-layer signaling.

[0424] According to an embodiment of the present disclosure, reporting the TA value may refer to reporting the TTA value or N in the above equation. TA,UE-specific Alternatively, the base station can configure and report TTA and N to the terminal through SIB or high-level signaling. TA,UE-specific Which one of them.

[0425] The reference time for determining the TA value reported by the terminal and the time for reporting the TA value may be determined based on the time when the terminal performs the TA value report, the time when the TA value report is triggered, etc. For example, when the TA value report is triggered by DCI in time slot n, the terminal may report the TA value applied or calculated in time slot nK, and the terminal may report the TA value to the base station in time slot n+N. K and N may be values ​​determined according to the subcarrier spacing, UE capability, time slot DL / UL configuration, and PUCCH resource configuration, respectively.

[0426] According to an embodiment of the present disclosure, K may be 0. K=0 may mean that the terminal reports the TA value based on the time at which the TA value report trigger signal is received. In addition, K may be a value less than 0, and in this case, for example, the TA value when the terminal reports the TA value may be calculated in advance, the report information may be generated and then reported. In addition, K may be an integer value greater than 0. This may be a TA value reported by the terminal earlier than the time (e.g., time slot n+N) at which the terminal reports the TA value, which may be a TA value reported at an earlier time because the terminal needs time to encode the information to be reported and prepare for transmission.

[0427] Fig.33 An example of a base station operation for reporting a TA value of a terminal according to an embodiment of the present disclosure is shown.

[0428] When reporting the TA value of the present disclosure, the TA value applied by the terminal may be indicated in units of ms, time slots, or symbols, or may be provided as information including values ​​below a decimal point instead of an integer. The report of the TA value of the present disclosure may include the absolute value of the TA, but may also include the TA value indicated by the previous base station or the relative TA value excluding the specified TA value or the amount of change in the TA value (for example, this may be the amount of change in the TA within a specific time period).

[0429] According to an embodiment of the present disclosure, the base station may transmit configuration information related to TA reporting through high-layer signaling (operation 3300). The configuration information related to TA reporting may include at least one of the information for configuring TA reporting, such as a period and offset for performing TA reporting, a TA reporting trigger condition, TA value reference point information, a type of TA information to be reported, resource configuration information on which TA reporting is performed, etc. The base station may trigger a TA report for the terminal (operation 3310). As an example, the trigger may be performed through high-layer signaling or DCI of the above-mentioned specific content, but may also be omitted. The base station may receive a TA report transmitted from the terminal according to the transmitted configuration information (operation 3320).

[0430] Fig.34 An example of a terminal operation for reporting a TA value of the terminal according to an embodiment of the present disclosure is shown.

[0431] When reporting the TA value of the present disclosure, the TA value applied by the terminal may be indicated in units of ms, time slots, or symbols, or may be provided as information including values ​​below a decimal point instead of an integer. The report of the TA value of the present disclosure may include the absolute value of the TA, but may also include the TA value indicated by the previous base station or the relative TA value excluding the specified TA value or the amount of change in the TA value (for example, this may be the amount of change in the TA within a specific time period).

[0432] According to an embodiment of the present disclosure, the terminal may receive configuration information related to TA reporting transmitted from a base station through high-layer signaling (operation 3430). The configuration information may include at least one of the information for configuring TA reporting, such as a period and offset for performing TA reporting, a TA report triggering condition, TA value reference point information, a type of TA information to be reported, resource configuration information on which TA reporting is performed, etc. The terminal may receive a signal for triggering TA reporting transmitted from a base station (operation 3440). As an example, the trigger may be performed through high-layer signaling or DCI of the above-mentioned specific content, but may also be omitted. The terminal transmits a TA report according to the received configuration information (3420). As an example, when TA report resource information is received, the terminal transmits a TA report from the configured resource. Fig.33 and Fig.34 Each step disclosed in the may be applied in a varied order, and other steps may be added or omitted.

[0433] The embodiment provides a method for a terminal to calculate, determine and report the N explained by the above embodiment. TA,UE-specific Method. TA,UE-specific The value may be calculated based on the distance between the terminal and a non-terrestrial network (NTN) satellite. The terminal may calculate its own position by receiving a signal from a navigation satellite in a satellite navigation system, and the navigation satellite may be different from the NTN satellite. Of course, the calculation of the terminal's own position is not limited to the above method, and the terminal's position may be received from another entity.

[0434] According to an embodiment of the present disclosure, a terminal can estimate the delay time between a satellite and a terminal based on its own position and the position of a satellite, and can perform uplink transmission by self-correcting the estimated delay time value. As an example, a satellite transmits information about a satellite position by broadcasting information, and a terminal can receive information about a satellite position transmitted from a satellite and compare the satellite position with its own position. The terminal's own position can be determined by using one of several types of global positioning system (GPS) systems independently or in combination or by information from a base station. Through the above comparison, the terminal can calculate the uplink transmission time by estimating the time it takes for a radio wave to be transmitted to a satellite.

[0435] For example, if the terminal receives a signal in time slot n through a downlink at a specific time, and can perform an uplink transmission corresponding to the signal in time slot n+k, the uplink transmission can be transmitted 2*Td earlier than time slot n+k. According to an embodiment of the present disclosure, the delay time Td can be a delay time from the terminal to the satellite or a value corresponding thereto calculated using the position information of the satellite and the terminal. The delay time Td can be the distance from the terminal to the satellite or a corresponding value divided by the speed of light or a value corresponding thereto. As an example, the position of the satellite can be a value calculated based on the time slot n+k in which the terminal performs the uplink transmission. This is because the position of the satellite in time slot n and the position of the satellite in time slot n+k may change according to the movement of the satellite.

[0436] In a terrestrial network, a propagation delay of less than 1 ms occurs considering that the distance to the base station is at most about 100 km, but in a satellite network, the distance to the satellite may be thousands of kilometers, and the distance from the satellite to the base station may also be thousands of kilometers, so the delay time may be much larger than in the case of a terrestrial network.

[0437] Fig.35 An example of the difference in propagation delay time between a terrestrial network and a satellite network according to an embodiment of the present disclosure is shown.

[0438] In satellite network communications, the delay time varies according to the altitude and elevation angle of the satellite, and Fig.35 The distance between the terminal and the satellite according to the elevation angle when the satellite is 700km above sea level, and the time it takes for the radio wave to travel back and forth are shown. In the case of a satellite network, a low-orbit satellite is assumed, and it is shown that when the elevation angle is 0 to 180°, the radio round-trip time (radio RTT, which may include the round-trip time it takes for a signal to be transmitted between a transmitter and a receiver and the processing time at another node) may be between 40.9ms and 9.3ms. According to an embodiment of the present disclosure, the delay time is only an example and may vary according to the altitude and orbit of the satellite, and, for example, at high altitudes, the average delay time may be further increased.

[0439] Since the maximum delay time in the terrestrial network is within 1ms or 2ms, the base station can match the time slot timing for transmitting the downlink and the time slot timing for receiving the uplink through the timing advance provided by the LTE and 5G NR systems (that is, the indexes of the DL time slot and the UL time slot can match). That is, if the terminal performs uplink transmission ahead of the downlink timing by the timing advance value indicated by the base station, when the uplink signal transmitted from the terminal is received by the base station, the uplink timing is consistent with the downlink timing of the base station. On the other hand, in a satellite network, it may be difficult for the base station to match the time slot timing for transmitting the downlink and the time slot timing for receiving the uplink through the timing advance provided in the conventional LTE and 5G NR systems. This is because the propagation delay time occurring in the satellite network is large, about tens of ms, and the propagation delay time is greater than the maximum value of the timing advance provided by the conventional LTE and 5G NR systems.

[0440] The satellite navigation system may also be referred to as a global navigation satellite system (GNSS), and the GNSS may include, for example, the GPS of the United States, the GLONASS of Russia, the Galileo of the European Union, the BeiDou of China, etc. Of course, not limited to the above examples. The GNSS may include a regional navigation satellite system (RNSS), and the RNSS may include, for example, the IRNSS of India, the QZSS of Japan, the KPS of South Korea, etc. On the other hand, the signal transmitted from the GNSS may include at least one of auxiliary navigation information, the normal operating status of the satellite, the satellite time, the satellite ephemeris, the satellite altitude, the reference time, and information about various correction data.

[0441] On the other hand, in various embodiments of the present disclosure, the NTN satellite may be a communication satellite that transmits a signal for the terminal to connect to the base station. In addition, in various embodiments of the present disclosure, the GNSS satellite may be a satellite that transmits a signal of a satellite navigation system. On the other hand, the terminal may receive a signal from each of one or more GNSS satellites, calculate its own position based on the signal received from each of the one or more GNSS satellites, and also identify the reference time of each of the one or more GNSS satellites. If the terminal can calculate its own position in a variety of ways based on signals received from multiple GNSS satellites, the terminal may calculate its actual position based on an average of multiple positions, a position corresponding to the strongest received signal among multiple positions, or an average of multiple positions based on signal strength (e.g., a method of applying a weight to a position corresponding to a signal with a stronger signal strength). Here, the method for the terminal to calculate its own position based on signals received from multiple GNSS satellites may be implemented in various forms, and its detailed description will be omitted.

[0442] In various embodiments of the present disclosure, the time obtained from the GNSS or the time of the base station transmitted by the base station may be based on, for example, the Coordinated Universal Time (UTC) time, which may be based on the time since 00:00:00 on January 1, 1900 in the Gregorian calendar. This may vary depending on the type of GNSS system, and a reference time zone as shown in Table 26 below may be used.

[0443]

Table 26

[0444]

[0445] In Table 26, NavIC may refer to navigation using the Indian constellation, QZS may refer to a Quasi-Zenith Satellite, QZSS may refer to a Quasi-Zenith Satellite System, QZST may refer to a Quasi-Zenith System Time, SBAS may refer to a Space-Based Augmentation System, and BDS may refer to a Beidou Navigation Satellite System.

[0446] In addition, through the satellite, the base station can indicate the type of the GNSS system as a reference for the position or time information used by the base station, and for example, an indicator as shown in Table 27 below can be used.

[0447]

Table 27

[0448] Value of gnss-TO-ID instruct 1 GPS 2 Galileo 3 QZS 4 GLONASS 5 BDS 6 NavIC 7 to 15 reserve

[0449] As described above, the terminal can calculate the time taken for the signal to be transmitted from the NTN satellite to the terminal based on the position of the terminal calculated by the terminal itself and the position of the NTN satellite received from the NTN satellite, and determine the TA value based on the calculated time. When determining the TA value, the terminal can also consider the distance from the NTN satellite to the base station on the ground, or if the signal is transmitted to the base station on the ground through another NTN satellite, the distance from the NTN satellite to another NTN satellite can be considered.

[0450] Conversely, the terminal can obtain reference time information based on information transmitted from GNSS satellites, compare the time information transmitted from NTN satellites with the reference time information obtained from GNSS satellites, and calculate the time required from the NTN satellite to the terminal (propagation delay) based on the comparison result.

[0451] The position and time information of NTN satellites can be transmitted from the base station to the terminal via SIB. This can be transmitted directly from the NTN satellite.

[0452] When the distance between the terminal and the satellite or the corresponding value of the distance is dUE,sat (unit km) and the speed of light is vc (unit km / sec), N can be determined based on dUE,sat / vc (unit sec) TA,UE-specific For example, N TA,UE-specificcan be determined and applied as And this is a way to The value is integerized to determine N TA,UE-specific Alternatively, the terminal may determine N by combining at least one of the following three methods: TA,UE-specific And N TA,UE-specific The information is reported to the base station.

[0453] -Method 3-1: The terminal can set N TA,UE-specific =(D+a) / T C . D is an integer, and a is a decimal greater than or equal to 0 and less than 1. Here, and Method 3-1 may be a method of dividing the propagation delay between the terminal and the satellite into an integer and a fractional part and reporting only the integer or a value corresponding thereto or reporting the integer and the fractional part or a value corresponding thereto, respectively. By using this method, the number of bits used to report the propagation delay can be reduced. Here, the fractional part is described above as an integer multiple of Tc, but it can be determined as 16·64 / 2 μ In the above, μ may refer to the subcarrier spacing of the current carrier, BWP or related CORESET. Alternatively, it may be a value used to transmit and receive signals such as PDSCH or PUSCH. Here, μ=0, 1, 2, 3, 4 and 5 may be values ​​corresponding to subcarrier spacings of 15kHz, 30kHz, 60kHz, 120kHz, 240kHz and 480kHz, respectively. Alternatively, μ may be configured for N by high-layer signaling from the base station. TA,UE-specific Alternatively, μ may be used as a fixed value, and as an example, it may be fixed to one of 0, 1, 2, 3, 4 or 5, such as μ=5.

[0454] -Method 3-2: The terminal can determine N TA,UE-specific It is 16.64 / 2 μ Multiples of N TA,UE-specific can be determined as In this disclosure, It may refer to the largest integer not greater than x, which may mean rounding the number down to an integer unit, that is, discarding the decimal value. Of course, it is not limited to the above examples, and instead of using Rounding down may be used, rounding up or rounding to decimal places may be used. In the above, μ may refer to the subcarrier spacing of the current carrier, BWP, SIB or related CORESET. Here, μ=0, 1, 2, 3, 4 and 5 may be values ​​corresponding to subcarrier spacings of 15kHz, 30kHz, 60kHz, 120kHz, 240kHz and 480kHz, respectively. Alternatively, μ may be configured for N by high-layer signaling from the base station. TA,UE-specific Alternatively, μ may be used as a fixed value, and as an example, it may be fixed to μ=5 for use. Alternatively, it may be used for N TA,UE-specific The calculated μ may be individually configured by the base station through SIB or higher layer signaling.

[0455] -Method 3-3: N TA,UE-specific =N A,UE-specific ·16·64 / 2 μ , and N A,UE-specific Can be set to make N A,UE-specific Closest to d UE,sat / (v c ·T c ). Alternatively, N A,UE-specific Can be set to satisfy The smallest integer, or N AUE-specific Can be set to satisfy The maximum integer.

[0456] Method 3-4: According to the base station configuration, the terminal can set N TA,UE-specific = 0. This may be because the propagation delay occurring in the link between the terminal and the satellite (which may be referred to as the service link) has little difference between the terminals within the coverage area of ​​a particular beam of the satellite, and thus the conventional TA mechanism and N TA,common To achieve uplink time synchronization. The base station can configure the terminal through SIB to set N TA,UE-specific The value is configured as N TA,UE-specific = 0, or use N calculated based on the position of the satellite and the terminal and the speed of light according to the GNSS signal TA,UE-specific As another example, the base station may configure, through SIB or separate RRC signaling, whether the terminal continuously uses N calculated based on the position of the satellite and the terminal and the speed of light according to the GNSS signal based on the time point of transmitting the PRACH preamble code. TA,UE-specific value until there is a separate instruction or configuration, or if the terminal uses a newly calculated N at each uplink transmission time TA,UE-specific That is, in the above equation 5, N TA,UE-specific The value can be determined as follows.

[0457] N TA,UE-specificis the TA estimated by the UE to pre-compensate for the serving link delay (if configured), otherwise, N TA,UE-specific is 0.

[0458] In methods 3-1 to 3-4, N is determined based on the distance between the terminal and the satellite (or its corresponding value) and the speed of light. TA,UE-specific The method is only an example, and there may be more methods. For example, generally, when N TA,UE-specific When a value is defined as an integer or an expression based on an integer value, it can be expressed as or N TA,UE-specific The value is expressed as a multiple of a specific integer or rational value K. Here, K can be a predetermined value or a value determined by a signaling parameter. Method 2 refers to K = 16·64 / 2 μ situation, and therefore, K can be based on factors such as μ or T c The advantage of this method is that it can express more diverse values ​​with the same bit signaling, but N TA,UE-specific The granularity of the values ​​is somewhat sparse. In addition, instead of using the floor calculations used in each of the above methods (such as ), the value can be rounded up based on the decimal place Or round off (Round(x)) to determine.

[0459] The embodiment provides a method for transmitting N signals explained in the above embodiment to a terminal by a base station. TA,common And the terminal performs calculations and applications.

[0460] The following is used for the base station to transmit N TA,common and methods of configuration and indication, and at least one or more of these methods may be applied in combination.

[0461] -Method 4-1: The base station can configure an offset value to the terminal through RRC signaling. The value configured through RRC signaling is called N A,common , and N TA,common Can be based on N A,common to be sure.

[0462] -Method 4-2: The base station can indicate an offset value to the terminal through MAC CE. The value configured through MAC CE is called N A,common , and N TA,common Can be based on N A,common Compared with the case of using the above method 4-1, the advantage of this method is that it allows the base station and the terminal to explicitly apply N TA,common As an example, N may be applied after a predetermined period of time based on the time of receiving a MAC CE or transmitting an ACK for receiving a MAC CE.TA,common As an example, the base station may transmit N in units of msec via MAC CE 8 bits. A,common And indicates from 0ms to 255ms. In this case, N A,common Determined as N A,common N TA,common =T A,common / (1000·Tc).

[0463] -Method 4-3: The base station may configure one or more offset values ​​to the terminal through high-level signaling. Alternatively, these values ​​may be pre-configured. These configured values ​​become T A,common candidate values, and the base station can indicate one of them through MAC CE.

[0464] -Method 4-4: The base station can configure an offset value for the terminal through SIB. The value configured through SIB is called T A,common , and N TA,common Can be based on T A,common By using N TA,common The terminal calculates and applies TA when transmitting the PRACH preamble during the initial access process. Thereafter, ΔT is indicated to the terminal via the MAC CE. A,common , and the terminal can use this to calculate N TA,common The change in N TA,common (New) = N TA,common (old)+(ΔT A,common -x)·y. In the above, x and y can be calculated according to the A,common For example, N TA,common (New) = N TA,common (old)+(ΔT A,common -M)·16·64 / 2 μ Here, the M value can be 31, and if the ΔT can be indicated by the MAC CE A,common The maximum value of is greater than 63, then M can be a value greater than or equal to 31. If ΔT A,common If the maximum value of is less than 63, then M can be less than or equal to 31.

[0465] -Method 4-5: The base station can indicate an offset value to the terminal through MAC CE. The configured value is called T A,common , and N TA,common Can be based on T A,common Compared with method 4-1, the advantage of this method is that the application N is clearly defined between the base station and the terminal. TA,commonAs an example, N may be applied after a predetermined period of time based on the time of receiving a MAC CE or transmitting an ACK for receiving a MAC CE. TA,common As an example, the base station can use MAC CE of about 19 or 24 bits to transmit the data at 16·64·Tc / 2. μ Transmit T in sec A,common In this case, N TA,common Determined as N TA,common =T A,common ·16·64 / 2 μ The number of bits of the MAC CE may be different from the above example.

[0466] -Method 4-6: The base station can indicate an offset value to the terminal through MAC CE. The configured value is called T A,common , and N TA,common It can be determined based on the altitude of the satellite. Compared with the case of using the above methods 4-5, the advantage of this method is that the number of bits that can be transmitted is reduced. As an example, the base station can use a MAC CE of about 16 bits to transmit at 16·64·Tc / 2 μ Transmit T in sec A,common In this case, N TA,common Determined to be In the above, h sat It can be the altitude of the satellite. This can mean that when the satellite is at a certain altitude, the minimum distance between the terminal and the satellite is a certain altitude, so the base station only needs to pass T A,common The number of bits of the MAC CE may be different from the above example.

[0467] In the above formula, The value may be defined by integerization or rationalization via a method similar to the above embodiment. For example, in the above embodiment, in addition to using a method such as or In addition to rounding down to integers or rationalization, we can also use h sat Value instead of d UE,sat Of course, integerization or rationalization similar to the above description can be applied to the entire value. For example, it can be defined as And in this case, it can be combined with Consider K = 16·64 / 2 μ In addition, the calculations used for integerization or rationalization can be applied not only to flooring, but also to various other operations, such as ceiling and rounding.

[0468] -Method 4-7: The base station can transmit N at the time of receiving through SIB TA,common Value and N TA,common The rate of change information. TA,common Value and N TA,common The change rate information may be transmitted to a specific terminal through RRC signaling instead of SIB, and the transmission method may vary according to the state (RRC_idle, RRC_inactive, RRC_connected) of the terminal.

[0469] N TA,common The rate of change information can be transmitted through one, two or three parameters through the SIB. As an example, if the rate of change information is transmitted through one parameter A, N is transmitted through the SIB. TA,common The time of N is called t1, and t2 is the time when uplink transmission is performed, then N TA,common (t2) (i.e., the terminal will apply N TA,common ) can be calculated as N TA,common (t2) = N TA,common (t1)+(t2-t1)·A. In this case, the unit of t1 and t2 may be msec, and the unit of A may be Tc / msec. That is, A may indicate N TA,common As another example, if the change rate information is transmitted through two parameters A and B, N is transmitted through SIB. TA,common The time of N is called t1, and t2 is the time when uplink transmission is performed, then N TA,common (t2) (i.e., the terminal will apply N TA,common ) can be calculated as N TA,common (t2) = N TA,common (t1)+(t2-t1)2·B+(t2-t1)·A (When the rate of change information is transmitted through n parameters, the difference between the two points (t2-t1) can also be expressed in the form of an n-order polynomial. In this case, the unit of t1 and t2 can be msec, and the unit of A can be T c / msec, and the unit of B can be T c / msec^2. That is, A can indicate N TA,common How much does the value change every 1msec? c , and B can indicate N TA,common How much does the value change every 1msec? c .

[0470] The embodiment provides a method for transmitting K from a base station to a terminal. offset A method and apparatus for determining a parameter at which a terminal transmits a second signal relative to a first signal transmitted from a base station.

[0471] When transmitting the first signal, the base station can indicate the time when the terminal transmits the corresponding second signal by using high-layer signaling and DCI. For example, when transmitting PDSCH, HARQ-ACK feedback for this can be indicated by the HARQ-ACK timing-related indicator in the bit field of the DCI that schedules PDSCH. However, in satellite communications, the delay time between the terminal and the base station is very large, so the offset value indicated in the conventional DCI may not indicate the correct timing. Therefore, the base station can transmit an additional timing offset Koffset value to the terminal via the SIB, and the terminal can determine the transmission timing (uplink transmission) of the second signal by adding the offset Koffset.

[0472] When the terminal is in the RRC_connected state after initial access, the base station can update the Koffset value to the terminal through RRC signaling. However, when the update is performed only through RRC signaling, the base station and the terminal may have different Koffsets during the time period when the RRC reconfiguration occurs. In this case, correct transmission and reception of the second signal may not occur. In order to eliminate this ambiguous time period, the base station can configure multiple Koffset values ​​to the terminal and indicate one of the configured Koffset values ​​through MAC CE. Therefore, the terminal can apply the updated Koffset value from a certain point in time after receiving the MAC CE.

[0473] As an example, through RRC signaling, the candidate Koffset value can be configured according to the index, as shown in Table 28 below.

[0474]

Table 28

[0475] index K_offset 0 100 1 120 2 140 3 160 4 180 5 200 6 220 7 240

[0476] Table 28 is an example of configuring Koffset at regular intervals through 8 indexes, and various other configurations are also possible. If the value of index i consists of 2M (M is an integer, such as 2, 3, 4, ...) such as 0, 1, 2, ..., 2M-1, and the Koffset value of index i is Koffset(i), then for i>0, it can be defined as a value with uniform intervals, such as Koffset(i) = Koffset(0) + (i-1) * A (A is a positive constant). Of course, the M value can vary according to the system configuration, and the A value can also be configured variably according to the M value. When the maximum value of Koffset other than the reserved field is Koffset(imax), there can be a relationship of A = (Koffset(imax)-Koffset(0)) / imax.

[0477] Of course, this is just an example configured with uniform difference values, and in general, it may not be composed of uniform difference values ​​as a whole. For example, different values ​​can be configured according to the range of the index, as follows (im value can be simply configured as 2M-1 or generally any other integer value).

[0478] 1≤i <im,

[0479] Koffset(i)=Koffset(0)+(i-1)*A1

[0480] im≤i≤imax,

[0481] Koffset(i)=Koffset(im)+(i-im)*A2

[0482] A1 and A2 are different positive constants, and A1 = (Koffset(im) - Koffset(0)) / im, A2 = (Koffset(imax) - Koffset(im)) / (imax - im).

[0483] Thereafter, the base station transmits an index to the terminal through a MAC CE in time slot n, and the terminal may transmit a second signal by applying the indicated Koffset in time slot n+k. According to an embodiment of the present disclosure, the value of k may be configured or determined according to the subcarrier spacing.

[0484] A terminal supporting a non-terrestrial network (NTN) may also operate in a terrestrial network (TN). When the radio access method operating in a terrestrial network (e.g., 3GPP NR) is different from the radio access method operating in a satellite network (e.g., 3GPP LTE NB-IoT), the terminal may operate by turning on only one radio access method because heterogeneous radio access methods cannot be turned on at the same time, or because turning them on at the same time is disadvantageous in terms of power consumption. Turning on the radio access may refer to running at least one of a chip or hardware device or software device that supports the radio access. In this case, the terminal may need a method for determining whether the network to be accessed is an NTN or a TN.

[0485] Fig.36 A flow chart of a terminal accessing a satellite network according to an embodiment of the present disclosure is shown.

[0486] In operation 3600, the terminal may attempt to access the terrestrial network, but determine that the terrestrial network cannot be accessed. For example, it can be assumed that the terminal preferentially uses a wireless access method associated with the terrestrial network. In this case, when no synchronization signal and / or reference signal transmitted from the terrestrial network is searched, the terminal can turn off the wireless access method of the terrestrial network and try the wireless access method of the satellite network.

[0487] In operation 3610, the terminal may determine the requirements for satellite network access. For example, the terminal may decide whether to use a wireless access method of a satellite network based on information related to the requirements for satellite network access.

[0488] As an example, in the case where the terminal has hardware capable of receiving GPS signals, the wireless access method of the satellite network can be enabled only when the GPS signal is captured, and the wireless access method of the satellite network can not be enabled when the GPS signal is not captured. For example, only when the GPS signal reception strength of the terminal is a specific threshold or higher, the terminal can determine that the GPS signal is captured, and / or the location information of the terminal can be determined within a specific error range through the GPS signal.

[0489] In another example, the terminal user can independently decide whether to use the wireless access method of the satellite network through the terminal, and the condition for activating the terminal so that the terminal user can decide whether to use the wireless access method of the satellite network may include the situation where the ground network signal of the terminal is not obtained and / or the GPS signal is obtained. If the condition is not met, the terminal user may not be able to turn on the wireless access method of the satellite network.

[0490] When the wireless access method of the satellite network is started, in operation 3620, the terminal can access the satellite network, and when the terminal completes the initial access and receives relevant advanced information from the satellite network, in operation 3630, the terminal can transmit and receive control and data information to and from the satellite.

[0491] Although the above explanation is for the case where the wireless access method of the terrestrial network and the wireless access method of the satellite network are different, there may also be a case where the wireless access method of the terrestrial network and the satellite network are the same. In this case, the above operation and condition determination may not be necessary.

[0492] One method for distinguishing between a terrestrial network and a satellite network may be to determine whether satellite related information is included by system information (or system information block; may be referred to as SIB) received by a terminal. Examples of satellite related information may include satellite position and velocity information and / or the effective time of satellite information. When satellite related information is not included in the system information, the terminal may determine the wireless access method using the terrestrial network. A base station or a base station connected to a ground station may distinguish whether a terminal accessing a network is a terminal accessing a terrestrial network or a terminal accessing a satellite network by at least one of a time resource, a frequency resource, a code, a preamble, or a sequence through which the terminal performs initial access. For example, when terminal A performs initial access through resource 1 and terminal B performs initial access through resource 2, the base station may determine that terminal A performs initial access through the terrestrial network and terminal B performs initial access through the satellite network. In this case, the base station may distinguish between initial access resources for the terrestrial network and initial access resources for the satellite network in advance. Additionally, even if the terminal accesses the same satellite network, the base station may distinguish between terminals with different capabilities in a manner similar to that described above.

[0493] The terminal may perform initial access to access a satellite network or a terrestrial network.

[0494] Fig.37 The initial access process according to an embodiment of the present disclosure is shown.

[0495] In operation 3700, the terminal may determine resource information for transmitting Message 1 (or a physical random access channel (PRACH)) based on system information received from a base station or a satellite before performing initial access, and transmit Message 1 from the resource.

[0496] In operation 3710, the terminal may receive Message 2 (or a random access response) from a base station or a satellite. Specifically, the terminal may receive DCI scrambled with a random access (RA)-RNTI from a base station or a satellite through a PDCCH, and receive Message 2 from a PDSCH resource indicated by the DCI.

[0497] In operation 3720 , the terminal may transmit Message 3 to the base station or the satellite through the PUSCH using resources indicated by the information included in Message 2 .

[0498] In operation 3730, the base station or satellite may transmit message 4 to the terminal through the PDSCH, and the PDSCH may be scheduled through the DCI scrambled by the temporary cell (TC)-RNTI in the PDCCH. Alternatively, the corresponding PDSCH may be scheduled through the DCI scrambled by the cell (C)-RNTI in the PDCCH. In addition, the PUCCH resource containing the HARQ-ACK information for reporting to the base station or satellite whether the demodulation / decoding of the corresponding PDSCH is successful may also be indicated through the DCI.

[0499] In operation 3740, the terminal may transmit HARQ-ACK information on whether demodulation / decoding of the PDSCH is successful to the base station or the satellite using the PUCCH resources indicated by the DCI.

[0500] One of the main characteristics of satellite networks compared to terrestrial networks is that the distance between the transmitting end and the receiving end is very long, which means that the received strength of the signal transmitted by the transmitting end at the receiving end may be very low. Therefore, in the case of satellite networks, a technology may be needed to increase the received strength by repeatedly transmitting the same information. Usually, the transmit power of the terminal is much lower than the transmit power of the satellite, so from the perspective of the uplink, the received strength may be much lower than that of the downlink. Therefore, a method is needed to support repeated PUCCH transmissions, which include HARQ-ACK information for the PDSCH containing message 4 information. In order to support PUCCH repeated transmission, at least one or a combination of the following methods may be considered.

[0501] -Method 7-1: Information related to PUCCH repetition transmission may be transmitted through a higher layer signal (eg, an RRC message), and the terminal may perform PUCCH repetition transmission including HARQ-ACK information for a PDSCH including Message 4 information.

[0502] Information related to PUCCH repetitive transmission can be transmitted to the terminal performing initial access in various forms. For example, information related to PUCCH repetitive transmission can be transmitted by being included in a high-level signal group or message containing NTN related information. In addition, information about a single number or multiple numbers for repeated transmission can be transmitted to the terminal. For example, when a single information element for repeated transmission is transmitted and the corresponding value is 4, the terminal can perform PUCCH repetitive transmission on 4 time slots, including HARQ-ACK information for the PDSCH containing message 4 information. In this case, for each time slot, the repeatedly transmitted PUCCH can have the same starting symbol and the same symbol length. In this case, the PUCCH format to which repeated transmission is applied may only be applicable to a specific PUCCH format. For example, the terminal can perform repeated transmission only on PUCCH format 1, and even when the repeated transmission value is transmitted as a high-level signal, the terminal can perform a single transmission on PUCCH format 0.

[0503] For another example, when multiple information elements for repeated transmission are transmitted by a high-level signal and the corresponding values ​​are {1, 2, 4, 8}, one of the multiple repeated transmission times can be determined according to the specific value of the field included in the DCI. The DCI schedule includes a PUCCH for HARQ-ACK information for a PDSCH containing message 4 information. For example, [Table 29] is an example of a field included in a DCI format according to an embodiment. The DCI format schedule includes a PUCCH for HARQ-ACK information for a PDSCH containing message 4 information. In this case, the number of repeated transmissions can be notified by at least one field in addition. For example, in [Table 29], a value in {1, 2, 4, 8} can be indicated to the terminal by using the 2 most significant bits (MSBs) of a 3-bit PUCCH resource indicator. The information provided by the existing 3-bit PUCCH resource indicator can be maintained, and additional repeated transmission information can be indicated. For example, the number of PUCCH repeated transmissions can be added and configured for each index in the PUCCH resource information in Table 31 described later. Alternatively, a new table including the number of PUCCH repetition transmissions (eg, PUCCH resource information in Table 31) may be configured as a higher layer signal.

[0504]

Table 29

[0505]

[0506]

[0507] According to an embodiment of the present disclosure, the terminal may receive high-level signal information related to repeated transmission of a PUCCH including HARQ-ACK information for a PDSCH including message 4 information only in a satellite network. For example, when information related to repeated transmission of a PUCCH including HARQ-ACK information for a PDSCH including message 4 information is not configured as a high-level signal, the terminal may determine to use a terrestrial network. Alternatively, regardless of the satellite network and the terrestrial network, information related to repeated transmission of a PUCCH including HARQ-ACK information for a PDSCH including message 4 information may be similarly applied.

[0508] Even if the terminal accesses the satellite network, there may be terminals that can perform repeated PUCCH transmissions, while there may be terminals that cannot perform repeated PUCCH transmissions. Therefore, the base station or satellite may need to distinguish these terminals in advance. For example, when the base station or satellite transmits a high-level signal containing information about whether to repeat the transmission of a PUCCH containing HARQ-ACK information for a PDSCH containing message 4 information, information about allocating a separate message 1 resource (e.g., at least one of a time resource, a frequency resource, a code, a preamble, or a sequence) to a terminal that receives the corresponding information and attempts to perform repeated PUCCH transmissions may be additionally included in the high-level signal. By this, the base station or satellite can determine that a terminal that has performed message 1 access through a separate message 1 resource is a terminal that can perform repeated PUCCH transmissions including HARQ-ACK information for a PDSCH containing message 4 information. Alternatively, when message 3 is transmitted through PUSCH, message 3 may include information indicating whether the terminal is able to perform repeated PUCCH transmissions including HARQ-ACK information for a PDSCH containing message 4.

[0509] -Method 7-2: Information related to PUCCH repetition transmission may be transmitted through a higher layer signal and a repetition transmission field in DCI, and the terminal may perform repetition transmission of the PUCCH including HARQ-ACK information for the PDSCH including the Message 4 information.

[0510] For example, when the terminal receives information through a high-layer signal that repeated transmission of a PUCCH including HARQ-ACK information for a PDSCH including message 4 information is performed, the terminal may determine a DCI format for scheduling a PDSCH including message 4 information and a PUCCH including HARQ-ACK therefor, as shown in Table 30. Compared to Table 29, if the PUCCH resource indicator in Table 29 consists of 3 bits, Table 30 may include a 1-bit PUCCH resource indicator and a 2-bit PUCCH repetition factor.

[0511] When there is no separate high-level signal, the 2-bit PUCCH resource factor can indicate one of the PUCCH repetition times {1, 2, 4, 8}. Alternatively, when separate information related to the number of PUCCH repetition transmissions is configured by a high-level signal, the PUCCH resource factor can be determined based on the information. For example, information related to the number of PUCCH repetition transmissions, such as {first repetition transmission value, second repetition transmission value, third repetition transmission value, and fourth repetition transmission value}, is transmitted by a high-level signal, and at least one of the four values ​​configured as a high-level signal can be indicated to the terminal by the 2-bit PUCCH repetition factor in the corresponding DCI format. This method is only an example, and the size of the PUCCH resource factor can be 1 bit or 3 bits. In this case, a total of 2 or 8 repetition transmission values ​​can be indicated, respectively.

[0512]

Table 30

[0513]

[0514]

[0515] The following Table 31 describes the PUCCH resources and format mapped to the PUCCH resource indicator in the DCI format composed of Table 29. In addition to the 3-bit information of the PUCCH resource indicator, one of the 16 PUCCH indexes in Table 31 can be indicated to the terminal by additionally using the CCE index information in the PDCCH region in which the DCI is received.

[0516] In Table 30, since there is a 1-bit PUCCH resource indicator, the terminal can additionally use the CCE index information in the PDCCH region in which the DCI is received to indicate one of the four PUCCH indexes in Table 31 to the terminal. Unlike TN, in NTN, the distance between the transmitter and the receiver is long, so when transmitting PUCCH, it may be advantageous to transmit a PUCCH including as many symbols as possible within a time slot. Therefore, the four PUCCH indexes may correspond to the indexes {12, 13, 14, 15} in Table 31. That is, one value of the indexes {12, 13, 14, 15} in Table 31 may be indicated to the terminal by a 1-bit PUCCH resource indicator and CCE index information. This is only an example, and other combinations other than the indexes {12, 13, 14, 15} may be selected, or which combination of the 16 indexes may be determined by an upper layer signal. In this case, when determining the format of the DCI for receiving message 4 PDSCH that the terminal searches for, different DCI formats may be determined according to TN and NTN. For example, the terminal may determine the format of the DCI that the terminal searches for as the DCI format in Table 29 when operating in the TN, and determine as the DCI format in Table 30 when operating in the NTN.

[0517]

Table 31

[0518]

[0519]

[0520] As another method, the base station or satellite may use a downlink assignment index consisting of 2 bits to indicate to the terminal one of the values ​​{1, 2, 4, 8} by which the PUCCH is repeatedly transmitted. The reason for considering the downlink assignment index is because it is a field that is not used in the DCI that schedules message 4 in the terrestrial network. Alternatively, the base station or satellite may use 2 bits of the 4-bit HARQ process number to indicate to the terminal one of the repeatedly transmitted PUCCH values ​​{1, 2, 4, 8}, and use only the remaining 2 bits of information to indicate one of the information in HARQ process numbers 1 to 4. The reason for considering the HARQ process number is that when scheduling message 4 in the terrestrial network, the terminal does not need to operate a large number of HARQ processes. Alternatively, the base station or satellite may use 2 bits of the 5-bit MCS information to indicate to the terminal one of the repeatedly transmitted PUCCH values ​​{1, 2, 4, 8}, and use only the remaining 3 bits of information to indicate one of the information in MCS indexes 1 to 8. The reason for considering MCS is that when scheduling message 4 in the ground network, unlike TN, NTN basically has an extremely low signal-to-noise ratio at the receiving end, so an MCS with a low code rate and modulation order may be selected. The above description can be applied to the case where the terminal is determined to operate as NTN, and can be interpreted as an existing field in TN. The above description is only an example, and a specific bit field in Table 29 or Table 30 may be used.

[0521] -Method 7-3: When the terminal performs repeated transmission of message 3, the terminal may repeatedly transmit the PUCCH including HARQ-ACK information for message 4 PDSCH. Before repeatedly transmitting message 3 PUSCH, the terminal may notify the base station or satellite whether to perform repeated transmission of message 3 PUSCH through PRACH resource selection for message 1 transmission. If the terminal requests the base station or satellite to perform repeated transmission of message 3 PUSCH by selecting a specific PRACH resource for message 1 transmission, the base station or satellite may notify whether message 3 PUSCH can be repeatedly transmitted by using 2-bit MSB information in the MCS field in the message 2 information.

[0522] Table 32 is an example of a method for using 2-bit MSB information in the MCS field to indicate whether to repeatedly transmit message 3PUSCH or the number of repeated transmissions. For example, when there is a separate high-layer signal configuration for whether to repeatedly transmit message 3PUSCH or the number of repeated transmissions, the 2-bit MSB of the MCS field can indicate a value in the high-layer signal information configured for each code point. If there is no separate high-layer signal configuration for repeated transmission or the number of repeated transmissions of message 3PUSCH, the terminal can apply a default value, and as an example in Table 32, the 2-bit MSB of the MCS field can indicate one of the values ​​1, 2, 3, and 4.

[0523]

Table 32

[0524]

[0525] Similarly, as shown in the example in Table 32, the terminal may indicate the number of repetitions of the PUCCH including the HARQ-ACK information for the message 4 PDSCH according to the code point indicated by the 2-bit MSB of the MCS field. For example, when the code point is 00, the number of repetitions of the PUCCH transmission may be 1, when the code point is 01, the number of repetitions of the PUCCH transmission may be 2, when the code point may be 10, the number of repetitions of the PUCCH transmission may be 4, and when the code point is 11, the number of repetitions of the PUCCH transmission may be configured as 8. This method may be applied only in the absence of a high-layer signal indicating the repetition of the PUCCH transmission. If there is a high-layer signal related to the repetition of the PUCCH, the terminal may apply the number of repetitions of the PUCCH configured as the high-layer signal for each code point. Alternatively, if the number of repetitions of the message 3 PUSCH configured using a separate upper layer signal is 2, 4, or 8 or more, the number of repetitions of the PUCCH including the HARQ-ACK information for the message 4 PDSCH may be selected as at least one of 2, 4, or 8.

[0526] -Method 7-4: When the terminal performs repeated transmission of message 1 or repeated transmission of message 3, the PUCCH including HARQ-ACK information for PDSCH of message 4 may be repeatedly transmitted. The high-layer signal configuration related to repeated transmission of message 1 and the information related to repeated transmission of message 3 may be transmitted as separate high-layer signals, or may be transmitted as the same high-layer signal.

[0527] When the terminal performs at least one of repeated transmission of message 1 and repeated transmission of message 3, the terminal may perform repeated transmission of PUCCH including HARQ-ACK information for message 4 PDSCH, and may apply at least one or a combination of the methods described in methods 7-1 to 7-3 as a method for repeated transmission of PUCCH including HARQ-ACK information for message 4 PDSCH. For example, if the terminal does not perform repeated transmission of message 1 and repeated transmission of message 3, the terminal may not perform repeated transmission of PUCCH including HARQ-ACK information for message 4 PDSCH. Alternatively, the terminal may determine whether to repeatedly transmit PUCCH including HARQ-ACK information for message 4 PDSCH based on the resource (e.g., time resource, frequency resource, code, preamble, or sequence) region selected when transmitting message 1.

[0528] Alternatively, when the terminal performs both repeated transmission of message 1 and repeated transmission of message 3, the terminal may perform repeated transmission of PUCCH including HARQ-ACK information for message 4 PDSCH, and at least one or a combination of the methods described in the above methods 7-1 to 7-3 may be applied as a method of repeated transmission of PUCCH including HARQ-ACK information for message 4 PDSCH. For example, when the terminal does not perform repeated transmission of message 1 and repeated transmission of message 3 or performs only one, the terminal may not perform repeated transmission of PUCCH including HARQ-ACK information for message 4 PDSCH.

[0529] Alternatively, when the terminal performs repeated transmission of message 1 or repeated transmission of message 3, the number of repeated transmissions of the PUCCH including HARQ-ACK information for the message 4 PDSCH may depend on whether repeated transmission of only message 1, repeated transmission of only message 3, or repeated transmission of both message 1 and message 3 is performed. For example, when repeated transmission of only message 1 is performed, the number of repeated transmissions of the PUCCH including HARQ-ACK information for the message 4 PDSCH may be 2, when repeated transmission of only message 1 is performed, the number of repeated transmissions of the PUCCH including HARQ-ACK information for the message 4 PDSCH may be 4, and when repeated transmission of both message 1 and repeated transmission of message 3 are performed, the number of repeated transmissions of the PUCCH including HARQ-ACK information for the message 4 PDSCH may be 8. The above-mentioned PUCCH repeated transmission number values ​​are only examples, and the PUCCH repeated transmission number values ​​may be different, and some values ​​may be the same. Additionally, the value of the number of PUCCH repetition transmissions may be configured in advance through a higher layer signal, and when there is no higher layer signal, a default value (eg, {1, 2, 4, 8}) may be used.

[0530] The embodiment describes a method for supporting frequency hopping when a terminal repeatedly transmits a PUCCH including HARQ-ACK information for a message 4 PDSCH. When a terminal operating in a satellite network is configured to perform frequency hopping on repeated transmission of PUCCH between time slots according to a high-level signal configuration, the terminal can perform frequency hopping in each time slot. When the time slot indicated to the terminal for the first repetition of PUCCH transmission is "time slot 0" and the terminal transmits PUCCH in a time slot equal to the number of PUCCH repeated transmissions, each subsequent time slot can be counted in the number of PUCCH repeated transmissions, regardless of whether the terminal actually transmits PUCCH in the time slot. In this case, the terminal can transmit PUCCH from the first PRB configured by the first high-level signal information in an even-numbered time slot (including "time slot 0") among multiple time slots for repeated PUCCH transmission, and transmit PUCCH from the second PRB provided by the second high-level signal information in an odd-numbered time slot among multiple time slots for repeated PUCCH transmission.

[0531] The high-layer signal information may be terminal common information or terminal specific information, and when the high-layer signal information is not configured for the terminal, a default value may be used.

[0532] Alternatively, when the first high-layer signal information and the second high-layer signal information include a plurality of PRB values, the base station or the satellite may indicate one PRB value to the terminal through an L1 signal (eg, DCI).

[0533] Alternatively, only the frequency start information (A_hop) of the PUCCH resources transmitted in the even (or odd) time slot can be provided to the terminal through the high-layer signal or the L1 signal, and the frequency start information of the PUCCH resources transmitted in the time slot with the odd (or even) number can have the relationship of (A_hop+X) mod(UL_BWP). Here, X can mean an offset value representing the frequency difference from A_hop, and UL_BWP can mean the size of the uplink BWP (e.g., the number of PRBs) through which the PUCCH including the HARQ-ACK information for the PDSCH containing the message 4 information is transmitted. The values ​​of X and UL_BWP can be sent to the terminal separately or transmitted to the terminal together as separate upper layer signals. Alternatively, when there is no separate high-layer signal for the value of X and UL_BWP, a default value can be applied. For example, when there is no separate high-layer signal for X, X can have one of the following values: floor(UL_BWP / 2), ceiling(UL_BWP / 2), or round(UL_BWP / 2).

[0534] When the terminal performs repeated transmission of the PUCCH including the HARQ-ACK information for the message 4 PDSCH, the frequency hopping information may be transmitted to the terminal using a higher layer signal and / or an L1 signal.

[0535] Specifically, in a high-layer signal group or message containing satellite network information, frequency hopping information applied during repeated PUCCH transmission including HARQ-ACK information for message 4PDSCH may be included. Alternatively, in a high-layer signal group or message containing satellite network information, it may be indicated whether the frequency hopping information applied during repeated PUCCH transmission including HARQ-ACK information for message 4PDSCH is included in the DCI format for scheduling the PUCCH including HARQ-ACK information for message 4PDSCH. In this case, a new field for indicating the frequency hopping information may be added to the DCI format of Table 29 or Table 30, or the frequency hopping information may be indirectly indicated by utilizing a field in an existing DCI format. For example, the frequency hopping information may be indirectly indicated based on whether the HARQ process number in the existing DCI format is an even number or an odd number. Alternatively, the frequency hopping information may be indicated by 1 bit in a field that is not used in a terrestrial network such as a downlink assignment index (DAI). Alternatively, in an unused field in a terrestrial network such as DAI, 1 bit may be used to indicate frequency hopping information, and the remaining 1 bit may be used to indicate whether the PUCCH including the HARQ-ACK information for message 4PDSCH is repeatedly transmitted or to indicate the number of repeated transmissions, similar to as explained in the above embodiments.

[0536] In the case where high-layer signal information is not configured, when high-layer signal information related to the satellite network (e.g., satellite orbit or speed information, etc.) is received, the terminal can determine that the relevant DCI format is configured as in the above example. Alternatively, when frequency hopping information is provided only as a high-layer signal and repeated PUCCH transmissions including HARQ-ACK information for message 4 PDSCH are scheduled, the terminal can assume that frequency hopping is always in operation.

[0537] As another embodiment, when a PUCCH including HARQ-ACK information for message 4PDSCH is repeatedly transmitted, the terminal may or may not perform frequency hopping. For example, when only one PUCCH including HARQ-ACK information for message 4PDSCH is transmitted, the terminal may perform intra-slot frequency hopping, and when the PUCCH including HARQ-ACK information for message 4PDSCH is repeatedly transmitted two or more times, the terminal may not perform frequency hopping. As another example, when only one PUCCH including HARQ-ACK information for message 4PDSCH is transmitted, the terminal may perform intra-slot frequency hopping, and when the PUCCH including HARQ-ACK information for message 4PDSCH is repeatedly transmitted two or more times, the terminal may perform inter-slot frequency hopping. As another example, when only one PUCCH including HARQ-ACK information for message 4PDSCH is transmitted, the terminal can perform intra-time slot hopping, and even when the PUCCH including HARQ-ACK information for message 4PDSCH is repeatedly transmitted two or more times, the terminal can perform intra-time slot hopping. In other words, the terminal can perform intra-time slot hopping regardless of the number of repetitions of the PUCCH including HARQ-ACK information for message 4PDSCH. As another example, whether to perform intra-time slot hopping, inter-time slot hopping, or no frequency hopping can be determined in advance based on the number of time slots through which the PUCCH including HARQ-ACK information for message 4PDSCH is transmitted. Alternatively, the frequency hopping method according to the number of transmissions can be configured by a high-level signal provided separately by the base station.

[0538] Fig.42 Various frequency hopping methods according to embodiments of the present disclosure are shown.

[0539] refer to Fig.42 For example, not performing frequency hopping (4200) may mean that the frequency resources used for the repeatedly transmitted PUCCH are the same. For example, when PUCCHs 4202, 4204, 4206, and 4208 are repeatedly transmitted on four time slots (time slots #1 to #4), all repeated PUCCHs may be transmitted through the same frequency resources.

[0540] As an example, performing inter-slot frequency hopping (4210) may mean transmitting the PUCCH transmitted for each time slot through different frequency resources. For example, when PUCCH is repeatedly transmitted in four different time slots, PUCCH 4212 and 4216 transmitted in time slots #1 and #3 may be transmitted and received through a first frequency resource, and PUCCH 4214 and 4218 transmitted in time slots #2 and #4 may be transmitted and received through a second frequency resource. In other words, inter-slot frequency hopping may mean repeatedly transmitting PUCCH through different frequencies on a time slot-by-time slot basis. Therefore, inter-slot frequency hopping may be used when the number of PUCCH repetition transmissions is two or more.

[0541] As an example, performing intra-slot frequency hopping (4220) may mean transmitting a PUCCH transmitted in one slot through different frequency resources. For example, when transmitting a PUCCH resource consisting of a plurality of (e.g., 14) symbols, the first X (e.g., 7) symbols may be transmitted and received through a first frequency resource (or a first hop), and the remaining Y (e.g., 7) symbols may be transmitted and received through a second frequency resource (or a second hop). For example, PUCCHs 4221 and 4222 transmitted in slot #1 may be transmitted through different frequency bands. If the time resource of the PUCCH transmitted by the terminal has an even number of symbols, the PUCCH may be divided into the same number of symbols, and intra-slot frequency hopping may be performed. Alternatively, if the time resource of the PUCCH transmitted by the terminal has an odd number of symbols, one of the two PUCCHs separated by intra-slot frequency hopping in one slot may have one more symbol than the other PUCCH. However, the above description is only an example, and when the time resource of the PUCCH transmitted by the terminal has an even number of symbols, the PUCCH may be divided into different numbers of symbols and may perform intra-slot frequency hopping, and when the time resource of the PUCCH transmitted by the terminal has an odd number of symbols, one PUCCH may have two or more symbols than another PUCCH. Fig.42 In the embodiment, when PUCCH is repeatedly transmitted on four time slots, the first PUCCHs 4221, 4223, 4225 and 4227 may be transmitted and received through the first frequency resources, and the second PUCCHs 4222, 4224, 4226 and 4228 may be transmitted and received through the second frequency resources.

[0542] Although the above description is limited to PUCCH transmission including HARQ-ACK information for message 4PDSCH, the present disclosure is not limited thereto, and the description may also be applied to default PUCCH transmission-related operations that operate after initial access of the terminal and before receiving separate PUCCH-related high-layer signal configuration information. Alternatively, the description may also be applied to operations related to PUCCH transmission provided by the terminal through control information received via a terminal common control channel.

[0543] Fig.38 A flowchart showing an operation of a terminal performing repeated PUCCH transmission or frequency hopping including HARQ-ACK information for message 4 PDSCH according to an embodiment of the present disclosure is shown.

[0544] In operation 3800, the terminal may determine whether to attempt to access a satellite network. When the terminal decides to access a satellite network, in operation 3810, the terminal may receive high-layer information for satellite network access from a base station or a satellite. According to the sixth embodiment described above, operation 3810 may be applied only when the satellite network and the terrestrial network use different wireless access technologies. Depending on the terminal, operation 3810 may be omitted. In operation 3820, the terminal may apply high-layer signal information for satellite network access to perform satellite network access according to the information. Operation 3810 may perform initial access according to at least one of the methods described in the above embodiments or some or all of their combinations. After successfully performing the initial access, in operation 3830, the terminal may determine that it has successfully accessed the satellite network, and transmit and receive control and data information for data transmission and reception with a base station or a satellite.

[0545] In the above, for the convenience of explanation, the embodiments of the present disclosure have been described separately, but at least two or more embodiments may be combined because each embodiment includes operations related to each other. In addition, the methods of each embodiment are not mutually exclusive, and one or more methods may be performed in combination.

[0546] It is shown that the base station, satellite and terminal or the transmitter and receiver perform the transmission and reception methods of the above-mentioned embodiments of the present disclosure, and in order to perform these methods, the base station, satellite and terminal's receiver, processor, transmitter and receiver can each operate according to the embodiments.

[0547] Fig.39 The internal structure of a terminal according to an embodiment of the present disclosure is shown.

[0548] like Fig.39As shown, the terminal of the present disclosure may include a terminal receiver 3900, a terminal transmitter 3920, and a terminal processor 3910. Of course, it is not limited to the above examples, and the terminal may include more or less configurations. In addition, the terminal receiver 3900, the terminal transmitter 3920, and the terminal processor 3910 may be composed of one chip.

[0549] In an embodiment of the present disclosure, the terminal receiver 3900 and the terminal transmitter 3920 may be collectively referred to as a transceiver. The transceiver may transmit a signal to a base station and receive a signal from the base station. The signal transmitted and received by the terminal may include control information and data. To this end, the transceiver may be composed of an RF transmitter that up-converts and amplifies the frequency of the transmitted signal and an RF receiver that amplifies the received signal with low noise and performs down-conversion. Of course, the components of the transmitter and the receiver are not limited to the RF transmitter and the RF receiver. In addition, the transceiver may receive a signal through a radio channel and output the signal to the terminal processor 3910, and transmit the signal output from the terminal processor 3910 through the radio channel.

[0550] The terminal processor 3910 can control a series of processes so that the terminal can operate according to the above-mentioned embodiments of the present disclosure. For example, the terminal receiver 3900 can receive signals from a satellite or a ground base station and receive signals from a GNSS, and the terminal processor 3910 can transmit signals to a base station and receive signals from a base station according to the method described in the present disclosure. Thereafter, the terminal transmitter 3920 can transmit a signal by using a determined time point. In the present disclosure, the terminal processor 3910 can be defined as a circuit, a dedicated integrated circuit, or at least one processor. Of course, it is not limited to the above examples.

[0551] According to an embodiment of the present disclosure, the terminal may include a memory (not shown). The memory may store programs and data necessary for the operation of the terminal. In addition, the memory may store control information or data included in a signal obtained from the terminal. The memory may be composed of a storage medium such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

[0552] Fig.40 The internal structure of a satellite according to an embodiment of the present disclosure is shown.

[0553] like Fig.40As shown, the satellite of the present disclosure may include a satellite receiver 4000, a satellite transmitter 4020, and a satellite processor 4010. In the above, the receiver, the transmitter, and the processor may include multiple units. That is, the satellite may include a receiver and a transmitter for transmitting signals to and receiving signals from a terminal, and a receiver and a transmitter for transmitting signals to and receiving signals from a base station (as well as a receiver and a transmitter for receiving signals from other satellites and transmitting signals to other satellites). Of course, it is not limited to the above examples, and the satellite may include more or less configurations. In addition, the satellite receiver 4000, the satellite transmitter 4020, and the satellite processor 4010 may be composed of one chip.

[0554] In an embodiment of the present disclosure, the satellite receiver 4000 and the satellite transmitter 4020 may be collectively referred to as a satellite transceiver. The transceiver may transmit signals to and receive signals from a terminal and a base station. The signal may include control information and data. To this end, the transceiver may be composed of an RF transmitter that up-converts and amplifies the frequency of the transmitted signal and an RF receiver that amplifies the received signal with low noise and performs down-conversion. Of course, the components of the transceiver are not limited to the RF transmitter and the RF receiver. In addition, the transceiver may receive a signal through a radio channel and output the signal to the satellite processor 4010, and transmit the signal output from the satellite processor 4010 through a radio channel. The satellite processor 4010 may include a compensator (pre-compensator) for correcting frequency offset or Doppler shift, and may include a device that can track a position from GPS, etc. In addition, the satellite processor 4010 may include a frequency shift function that can shift the center frequency of the received signal. The satellite processor 4010 may control a series of processes so that the satellite, base station, and terminal can operate according to the above-mentioned embodiments of the present disclosure.

[0555] For example, the satellite receiver 4000 may receive a PRACH preamble from the terminal, send back a corresponding RAR to the terminal, and determine to transmit TA information to the base station. Thereafter, the satellite transmitter 4020 may transmit a corresponding signal at a determined time point. In the present disclosure, the satellite processor 4010 may be defined as a circuit, a dedicated integrated circuit, or at least one processor. Of course, it is not limited to the above examples.

[0556] According to an embodiment of the present disclosure, the satellite may include a memory (not shown). The memory may store programs and data necessary for the operation of the satellite. In addition, the memory may store control information or data included in a signal obtained from the satellite. The memory may be composed of a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0557] Fig.41The internal structure of a base station according to an embodiment of the present disclosure is shown.

[0558] like Fig.41 As shown, the base station of the present disclosure may include a base station receiver 4100, a base station transmitter 4120, and a base station processor 4110. The base station may be a part of a ground base station or a satellite. In an embodiment of the present disclosure, the base station receiver 4100 and the base station transmitter 4120 may be collectively referred to as a transceiver. The transceiver may transmit a signal to a terminal and receive a signal from the terminal. The signal transmitted and received with the terminal, another base station or a satellite may include control information and data. To this end, the transceiver may be composed of an RF transmitter that up-converts and amplifies the frequency of the transmitted signal and an RF receiver that amplifies the received signal with low noise and performs down-conversion. Of course, the components of the transmitter and the receiver are not limited to the RF transmitter and the RF receiver. In addition, the transceiver may receive a signal through a radio channel and output the signal to the base station processor 4110, and transmit the signal output from the base station processor 4110 through a radio channel. The base station processor 4110 may control a series of processes so that the base station can operate according to the above-mentioned embodiment of the present disclosure. For example, the base station 4110 may transmit a RAR including TA information. In the present disclosure, the base station processor 4110 may be defined as a circuit, a dedicated integrated circuit, or at least one processor. Of course, it is not limited to the above examples.

[0559] According to an embodiment of the present disclosure, the base station may include a memory (not shown). The memory may store programs and data necessary for the operation of the base station. In addition, the memory may store control information or data included in a signal obtained from the base station. The memory may be composed of a storage medium such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

[0560] The embodiments of the present disclosure described and shown in the specification and the drawings are only specific embodiments presented to facilitate explanation of the technical content of the present disclosure and to help understand the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is obvious to those skilled in the art that other variations based on the technical ideas of the present disclosure can be implemented. In addition, if necessary, the above-mentioned corresponding embodiments can be used in combination. In addition, based on the technical concepts of the embodiments, other variations of the above embodiments can also be implemented in LTE and 5G systems.

[0561] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: receiving, from a base station, configuration information related to a set of one or more numbers of repetitions for a physical uplink control channel, PUCCH; Receiving downlink control information DCI for scheduling a physical downlink shared channel PDSCH from the base station; receiving the PDSCH from the base station based on the DCI; determining a number of time slots for the PUCCH repetition based on the configuration information if the set of one or more numbers includes a single value, or determining a number of time slots for the PUCCH repetition based on the configuration information and the DCI if the set of one or more numbers includes more than one value; as well as A PUCCH including hybrid automatic repeat request acknowledgement (HARQ-ACK) information for the PDSCH is transmitted to the base station over the determined plurality of time slots.

2. The method according to claim 1, wherein: In case the set of one or more numbers includes more than one value, the downlink assignment index included in the DCI indicates the number of the plurality of time slots from the set of one or more numbers.

3. The method according to claim 1, wherein: The DCI is scrambled by a temporary cell radio network temporary identifier TC-RNTI.

4. The method according to claim 1, wherein: In case of performing a random access procedure with the base station, the PDSCH includes message 4, and Wherein, the method further comprises: During the random access procedure, a message 3 is transmitted to the base station before receiving the DCI, wherein the message 3 includes information indicating that the terminal supports repetition of the PUCCH having the HARQ-ACK information for the message 4.

5. A method performed by a base station in a wireless communication system, the method comprising: transmitting configuration information related to a set of one or more numbers of repetitions for a physical uplink control channel (PUCCH); Transmitting downlink control information DCI for scheduling a physical downlink shared channel PDSCH to the terminal; transmitting the PDSCH according to the DCI to the terminal; and In the case where the set of one or more numbers includes a single value, a PUCCH including hybrid automatic repeat request confirmation HARQ-ACK information for the PDSCH is received from the terminal on multiple time slots used for the PUCCH repetition according to the configuration information, or in the case where the set of one or more numbers includes more than one value, a PUCCH including hybrid automatic repeat request confirmation HARQ-ACK information for the PDSCH is received from the terminal on multiple time slots used for the PUCCH repetition according to the configuration information and the DCI.

6. The method according to claim 5, wherein: In case the set of one or more numbers includes more than one value, the downlink assignment index included in the DCI indicates the number of the plurality of time slots from the set of one or more numbers.

7. The method according to claim 5, wherein: The DCI is scrambled by a temporary cell radio network temporary identifier TC-RNTI.

8. The method according to claim 5, wherein: In case of performing a random access procedure with the terminal, the PDSCH includes message 4, and Wherein, the method further comprises: During the random access procedure, a message 3 is received from the terminal before the DCI is transmitted, wherein the message 3 includes information indicating that the terminal supports repetition of a PUCCH having HARQ-ACK information for the message 4.

9. A terminal in a wireless communication system, the terminal comprising: Transceiver; as well as A controller, the controller being configured to: receiving, via the transceiver, from a base station configuration information related to a set of one or more numbers of repetitions for a physical uplink control channel (PUCCH), receiving, via the transceiver, downlink control information DCI for scheduling a physical downlink shared channel PDSCH from the base station, receiving the PDSCH from the base station via the transceiver based on the DCI, determining a number of time slots for the PUCCH repetition based on the configuration information if the set of one or more numbers includes a single value, or determining a number of time slots for the PUCCH repetition based on the configuration information and the DCI if the set of one or more numbers includes more than one value, and A PUCCH including hybrid automatic repeat request acknowledgement (HARQ-ACK) information for the PDSCH is transmitted to the base station via the transceiver over the determined plurality of time slots.

10. The terminal according to claim 9, wherein: In case the set of one or more numbers includes more than one value, the downlink assignment index included in the DCI indicates the number of the plurality of time slots from the set of one or more numbers.

11. The terminal according to claim 9, wherein: The DCI is scrambled by a temporary cell radio network temporary identifier TC-RNTI.

12. The terminal according to claim 9, wherein: In case of performing a random access procedure with the base station, the PDSCH includes message 4, and Wherein, the controller is further configured as: During the random access procedure, a message 3 is transmitted to the base station via the transceiver before receiving the DCI, wherein the message 3 includes information indicating that the terminal supports repetition of the PUCCH having the HARQ-ACK information for the message 4.

13. A base station in a wireless communication system, the base station comprising: Transceiver; as well as A controller, the controller being configured to: transmitting, via the transceiver, configuration information related to a set of one or more numbers of repetitions for a Physical Uplink Control Channel (PUCCH), transmitting downlink control information DCI for scheduling a physical downlink shared channel PDSCH to a terminal via the transceiver, transmitting the PDSCH according to the DCI to the terminal via the transceiver, and The method comprises: receiving a PUCCH including hybrid automatic repeat request confirmation HARQ-ACK information for the PDSCH from the terminal via the transceiver on multiple time slots for the PUCCH repetition according to the configuration information when the set of one or more numbers includes a single value, or receiving a PUCCH including hybrid automatic repeat request confirmation HARQ-ACK information for the PDSCH from the terminal via the transceiver on multiple time slots for the PUCCH repetition according to the configuration information and the DCI when the set of one or more numbers includes more than one value.

14. The base station according to claim 13, wherein: In case the set of one or more numbers includes more than one value, the downlink assignment index included in the DCI indicates the number of the plurality of time slots from the set of one or more numbers, and The DCI is scrambled by a temporary cell radio network temporary identifier TC-RNTI.

15. The base station according to claim 13, wherein: In case of performing a random access procedure with the terminal, the PDSCH includes message 4, and Wherein, the controller is further configured as: During the random access procedure, a message 3 is received from the terminal via the transceiver before the DCI is transmitted, wherein the message 3 includes information indicating that the terminal supports repetition of a PUCCH having HARQ-ACK information for the message 4.

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